Plaintext
GNU Automake
For version 1.10.2, 23 November 2008
David MacKenzie
Tom Tromey
Alexandre Duret-Lutz
This manual is for GNU Automake (version 1.10.2, 23 November 2008), a program that
creates GNU standards-compliant Makefiles from template files.
Copyright c 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007,
2008 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document under
the terms of the GNU Free Documentation License, Version 1.3 or any later
version published by the Free Software Foundation; with no Invariant Sections,
with no Front-Cover texts, and with no Back-Cover Texts. A copy of the license
is included in the section entitled “GNU Free Documentation License.”
Chapter 2: An Introduction to the Autotools 1
1 Introduction
Automake is a tool for automatically generating Makefile.ins from files called
Makefile.am. Each Makefile.am is basically a series of make variable definitions1 , with
rules being thrown in occasionally. The generated Makefile.ins are compliant with the
GNU Makefile standards.
The GNU Makefile Standards Document (see Section “Makefile Conventions” in The
GNU Coding Standards) is long, complicated, and subject to change. The goal of Automake
is to remove the burden of Makefile maintenance from the back of the individual GNU
maintainer (and put it on the back of the Automake maintainers).
The typical Automake input file is simply a series of variable definitions. Each such
file is processed to create a Makefile.in. There should generally be one Makefile.am per
directory of a project.
Automake does constrain a project in certain ways; for instance, it assumes that the
project uses Autoconf (see Section “Introduction” in The Autoconf Manual), and enforces
certain restrictions on the configure.ac contents2 .
Automake requires perl in order to generate the Makefile.ins. However, the distribu-
tions created by Automake are fully GNU standards-compliant, and do not require perl in
order to be built.
Mail suggestions and bug reports for Automake to bug-automake@gnu.org.
2 An Introduction to the Autotools
If you are new to Automake, maybe you know that it is part of a set of tools called The
Autotools. Maybe you’ve already delved into a package full of files named configure,
configure.ac, Makefile.in, Makefile.am, aclocal.m4, . . . , some of them claiming to
be generated by Autoconf or Automake. But the exact purpose of these files and their
relations is probably fuzzy. The goal of this chapter is to introduce you to this machinery,
to show you how it works and how powerful it is. If you’ve never installed or seen such a
package, do not worry: this chapter will walk you through it.
If you need some teaching material, more illustrations, or a less automake-centered
continuation, some slides for this introduction are available in Alexandre Duret-Lutz’s
Autotools Tutorial (http://www-src.lip6.fr/~Alexandre.Duret-Lutz/autotools.
html). This chapter is the written version of the first part of his tutorial.
2.1 Introducing the GNU Build System
It is a truth universally acknowledged, that a developer in possession of a new package,
must be in want of a build system.
1
These variables are also called make macros in Make terminology, however in this manual we reserve the
term macro for Autoconf’s macros.
2
Older Autoconf versions used configure.in. Autoconf 2.50 and greater promotes configure.ac over
configure.in. The rest of this documentation will refer to configure.ac, but Automake also supports
configure.in for backward compatibility.
Chapter 2: An Introduction to the Autotools 2
In the Unix world, such a build system is traditionally achieved using the command make
(see Section “Overview” in The GNU Make Manual). The developer expresses the recipe to
build his package in a Makefile. This file is a set of rules to build the files in the package.
For instance the program prog may be built by running the linker on the files main.o,
foo.o, and bar.o; the file main.o may be built by running the compiler on main.c; etc.
Each time make is run, it reads Makefile, checks the existence and modification time of
the files mentioned, decides what files need to be built (or rebuilt), and runs the associated
commands.
When a package needs to be built on a different platform than the one it was developed
on, its Makefile usually needs to be adjusted. For instance the compiler may have another
name or require more options. In 1991, David J. MacKenzie got tired of customizing
Makefile for the 20 platforms he had to deal with. Instead, he handcrafted a little shell
script called configure to automatically adjust the Makefile (see Section “Genesis” in
The Autoconf Manual). Compiling his package was now as simple as running ./configure
&& make.
Today this process has been standardized in the GNU project. The GNU Coding Stan-
dards (see Section “Managing Releases” in The GNU Coding Standards) explains how each
package of the GNU project should have a configure script, and the minimal interface it
should have. The Makefile too should follow some established conventions. The result? A
unified build system that makes all packages almost indistinguishable by the installer. In
its simplest scenario, all the installer has to do is to unpack the package, run ./configure
&& make && make install, and repeat with the next package to install.
We call this build system the GNU Build System, since it was grown out of the GNU
project. However it is used by a vast number of other packages: following any existing
convention has its advantages.
The Autotools are tools that will create a GNU Build System for your package. Autoconf
mostly focuses on configure and Automake on Makefiles. It is entirely possible to create
a GNU Build System without the help of these tools. However it is rather burdensome and
error-prone. We will discuss this again after some illustration of the GNU Build System in
action.
2.2 Use Cases for the GNU Build System
In this section we explore several use cases for the GNU Build System. You can
replay all these examples on the amhello-1.0.tar.gz package distributed with
Automake. If Automake is installed on your system, you should find a copy of this file
in prefix/share/doc/automake/amhello-1.0.tar.gz, where prefix is the installation
prefix specified during configuration (prefix defaults to /usr/local, however if Automake
was installed by some GNU/Linux distribution it most likely has been set to /usr). If you
do not have a copy of Automake installed, you can find a copy of this file inside the doc/
directory of the Automake package.
Some of the following use cases present features that are in fact extensions to the GNU
Build System. Read: they are not specified by the GNU Coding Standards, but they are
nonetheless part of the build system created by the Autotools. To keep things simple, we
do not point out the difference. Our objective is to show you many of the features that the
build system created by the Autotools will offer to you.
Chapter 2: An Introduction to the Autotools 3
2.2.1 Basic Installation
The most common installation procedure looks as follows.
~ % tar zxf amhello-1.0.tar.gz
~ % cd amhello-1.0
~/amhello-1.0 % ./configure
...
config.status: creating Makefile
config.status: creating src/Makefile
...
~/amhello-1.0 % make
...
~/amhello-1.0 % make check
...
~/amhello-1.0 % su
Password:
/home/adl/amhello-1.0 # make install
...
/home/adl/amhello-1.0 # exit
~/amhello-1.0 % make installcheck
...
The user first unpacks the package. Here, and in the following examples, we will use the
non-portable tar zxf command for simplicity. On a system without GNU tar installed,
this command should read gunzip -c amhello-1.0.tar.gz | tar xf -.
The user then enters the newly created directory to run the configure script. This
script probes the system for various features, and finally creates the Makefiles. In this
toy example there are only two Makefiles, but in real-world projects, there may be many
more, usually one Makefile per directory.
It is now possible to run make. This will construct all the programs, libraries, and
scripts that need to be constructed for the package. In our example, this compiles the
hello program. All files are constructed in place, in the source tree; we will see later how
this can be changed.
make check causes the package’s tests to be run. This step is not mandatory, but it is
often good to make sure the programs that have been built behave as they should, before
you decide to install them. Our example does not contain any tests, so running make check
is a no-op.
After everything has been built, and maybe tested, it is time to install it on the sys-
tem. That means copying the programs, libraries, header files, scripts, and other data
files from the source directory to their final destination on the system. The command
make install will do that. However, by default everything will be installed in subdi-
rectories of /usr/local: binaries will go into /usr/local/bin, libraries will end up in
/usr/local/lib, etc. This destination is usually not writable by any user, so we assume
that we have to become root before we can run make install. In our example, run-
ning make install will copy the program hello into /usr/local/bin and README into
/usr/local/share/doc/amhello.
Chapter 2: An Introduction to the Autotools 4
A last and optional step is to run make installcheck. This command may run tests on
the installed files. make check tests the files in the source tree, while make installcheck
tests their installed copies. The tests run by the latter can be different from those run by the
former. For instance, there are tests that cannot be run in the source tree. Conversely, some
packages are set up so that make installcheck will run the very same tests as make check,
only on different files (non-installed vs. installed). It can make a difference, for instance
when the source tree’s layout is different from that of the installation. Furthermore it may
help to diagnose an incomplete installation.
Presently most packages do not have any installcheck tests because the existence of
installcheck is little known, and its usefulness is neglected. Our little toy package is no
better: make installcheck does nothing.
2.2.2 Standard Makefile Targets
So far we have come across four ways to run make in the GNU Build System: make,
make check, make install, and make installcheck. The words check, install, and
installcheck, passed as arguments to make, are called targets. make is a shorthand for
make all, all being the default target in the GNU Build System.
Here is a list of the most useful targets that the GNU Coding Standards specify.
make all Build programs, libraries, documentation, etc. (same as make).
make install
Install what needs to be installed, copying the files from the package’s tree to
system-wide directories.
make install-strip
Same as make install, then strip debugging symbols. Some users like to trade
space for useful bug reports. . .
make uninstall
The opposite of make install: erase the installed files. (This needs to be run
from the same build tree that was installed.)
make clean
Erase from the build tree the files built by make all.
make distclean
Additionally erase anything ./configure created.
make check
Run the test suite, if any.
make installcheck
Check the installed programs or libraries, if supported.
make dist Recreate package-version.tar.gz from all the source files.
2.2.3 Standard Directory Variables
The GNU Coding Standards also specify a hierarchy of variables to denote installation
directories. Some of these are:
Chapter 2: An Introduction to the Autotools 5
Directory variable Default value
prefix /usr/local
exec_prefix ${prefix}
bindir ${exec_prefix}/bin
libdir ${exec_prefix}/lib
...
includedir ${prefix}/include
datarootdir ${prefix}/share
datadir ${datarootdir}
mandir ${datarootdir}/man
infodir ${datarootdir}/info
docdir ${datarootdir}/doc/${PACKAGE}
...
Each of these directories has a role which is often obvious from its name. In a package,
any installable file will be installed in one of these directories. For instance in amhello-1.0,
the program hello is to be installed in bindir, the directory for binaries. The default
value for this directory is /usr/local/bin, but the user can supply a different value when
calling configure. Also the file README will be installed into docdir, which defaults to
/usr/local/share/doc/amhello.
A user who wishes to install a package on his own account could proceed as follows:
~/amhello-1.0 % ./configure --prefix ~/usr
...
~/amhello-1.0 % make
...
~/amhello-1.0 % make install
...
This would install ~/usr/bin/hello and ~/usr/share/doc/amhello/README.
The list of all such directory options is shown by ./configure --help.
2.2.4 Standard Configuration Variables
The GNU Coding Standards also define a set of standard configuration variables used during
the build. Here are some:
CC C compiler command
CFLAGS C compiler flags
CXX C++ compiler command
CXXFLAGS C++ compiler flags
LDFLAGS linker flags
CPPFLAGS C/C++ preprocessor flags
...
configure usually does a good job at setting appropriate values for these variables, but
there are cases where you may want to override them. For instance you may have several
versions of a compiler installed and would like to use another one, you may have header
Chapter 2: An Introduction to the Autotools 6
files installed outside the default search path of the compiler, or even libraries out of the
way of the linker.
Here is how one would call configure to force it to use gcc-3 as C compiler, use header
files from ~/usr/include when compiling, and libraries from ~/usr/lib when linking.
~/amhello-1.0 % ./configure --prefix ~/usr CC=gcc-3 \
CPPFLAGS=-I$HOME/usr/include LDFLAGS=-L$HOME/usr/lib
Again, a full list of these variables appears in the output of ./configure --help.
2.2.5 Overriding Default Configuration Setting with config.site
When installing several packages using the same setup, it can be convenient to create a file
to capture common settings. If a file named prefix/share/config.site exists, configure
will source it at the beginning of its execution.
Recall the command from the previous section:
~/amhello-1.0 % ./configure --prefix ~/usr CC=gcc-3 \
CPPFLAGS=-I$HOME/usr/include LDFLAGS=-L$HOME/usr/lib
Assuming we are installing many package in ~/usr, and will always want to use these
definitions of CC, CPPFLAGS, and LDFLAGS, we can automate this by creating the following
~/usr/share/config.site file:
test -z "$CC" && CC=gcc-3
test -z "$CPPFLAGS" && CPPFLAGS=-I$HOME/usr/include
test -z "$LDFLAGS" && LDFLAGS=-L$HOME/usr/lib
Now, any time a configure script is using the ~/usr prefix, it will execute the above
config.site and define these three variables.
~/amhello-1.0 % ./configure --prefix ~/usr
configure: loading site script /home/adl/usr/share/config.site
...
See Section “Setting Site Defaults” in The Autoconf Manual, for more information about
this feature.
2.2.6 Parallel Build Trees (a.k.a. VPATH Builds)
The GNU Build System distinguishes two trees: the source tree, and the build tree.
The source tree is rooted in the directory containing configure. It contains all the
sources files (those that are distributed), and may be arranged using several subdirectories.
The build tree is rooted in the directory in which configure was run, and is populated
with all object files, programs, libraries, and other derived files built from the sources (and
hence not distributed). The build tree usually has the same subdirectory layout as the
source tree; its subdirectories are created automatically by the build system.
If configure is executed in its own directory, the source and build trees are combined:
derived files are constructed in the same directories as their sources. This was the case in
our first installation example (see Section 2.2.1 [Basic Installation], page 3).
A common request from users is that they want to confine all derived files to a single
directory, to keep their source directories uncluttered. Here is how we could run configure
to build everything in a subdirectory called build/.
~ % tar zxf ~/amhello-1.0.tar.gz
Chapter 2: An Introduction to the Autotools 7
~ % cd amhello-1.0
~/amhello-1.0 % mkdir build && cd build
~/amhello-1.0/build % ../configure
...
~/amhello-1.0/build % make
...
These setups, where source and build trees are different, are often called parallel builds or
VPATH builds. The expression parallel build is misleading: the word parallel is a reference
to the way the build tree shadows the source tree, it is not about some concurrency in
the way build commands are run. For this reason we refer to such setups using the name
VPATH builds in the following. VPATH is the name of the make feature used by the
Makefiles to allow these builds (see Section “VPATH: Search Path for All Prerequisites” in
The GNU Make Manual).
VPATH builds have other interesting uses. One is to build the same sources with multiple
configurations. For instance:
~ % tar zxf ~/amhello-1.0.tar.gz
~ % cd amhello-1.0
~/amhello-1.0 % mkdir debug optim && cd debug
~/amhello-1.0/debug % ../configure CFLAGS=’-g -O0’
...
~/amhello-1.0/debug % make
...
~/amhello-1.0/debug % cd ../optim
~/amhello-1.0/optim % ../configure CFLAGS=’-O3 -fomit-frame-pointer’
...
~/amhello-1.0/optim % make
...
With network file systems, a similar approach can be used to build the same sources
on different machines. For instance, suppose that the sources are installed on a directory
shared by two hosts: HOST1 and HOST2, which may be different platforms.
~ % cd /nfs/src
/nfs/src % tar zxf ~/amhello-1.0.tar.gz
On the first host, you could create a local build directory:
[HOST1] ~ % mkdir /tmp/amh && cd /tmp/amh
[HOST1] /tmp/amh % /nfs/src/amhello-1.0/configure
...
[HOST1] /tmp/amh % make && sudo make install
...
(Here we assume that the installer has configured sudo so it can execute make install with
root privileges; it is more convenient than using su like in Section 2.2.1 [Basic Installation],
page 3).
On the second host, you would do exactly the same, possibly at the same time:
[HOST2] ~ % mkdir /tmp/amh && cd /tmp/amh
[HOST2] /tmp/amh % /nfs/src/amhello-1.0/configure
...
Chapter 2: An Introduction to the Autotools 8
[HOST2] /tmp/amh % make && sudo make install
...
In this scenario, nothing forbids the /nfs/src/amhello-1.0 directory from being read-
only. In fact VPATH builds are also a means of building packages from a read-only medium
such as a CD-ROM. (The FSF used to sell CD-ROM with unpacked source code, before the
GNU project grew so big.)
2.2.7 Two-Part Installation
In our last example (see Section 2.2.6 [VPATH Builds], page 6), a source tree was shared
by two hosts, but compilation and installation were done separately on each host.
The GNU Build System also supports networked setups where part of the installed
files should be shared amongst multiple hosts. It does so by distinguishing architecture-
dependent files from architecture-independent files, and providing two Makefile targets to
install each of these classes of files.
These targets are install-exec for architecture-dependent files and install-data for
architecture-independent files. The command we used up to now, make install, can be
thought of as a shorthand for make install-exec install-data.
From the GNU Build System point of view, the distinction between architecture-
dependent files and architecture-independent files is based exclusively on the directory
variable used to specify their installation destination. In the list of directory variables
we provided earlier (see Section 2.2.3 [Standard Directory Variables], page 4), all the
variables based on exec-prefix designate architecture-dependent directories whose files
will be installed by make install-exec. The others designate architecture-independent
directories and will serve files installed by make install-data. See Chapter 12 [Install],
page 91, for more details.
Here is how we could revisit our two-host installation example, assuming that (1) we
want to install the package directly in /usr, and (2) the directory /usr/share is shared by
the two hosts.
On the first host we would run
[HOST1] ~ % mkdir /tmp/amh && cd /tmp/amh
[HOST1] /tmp/amh % /nfs/src/amhello-1.0/configure --prefix /usr
...
[HOST1] /tmp/amh % make && sudo make install
...
On the second host, however, we need only install the architecture-specific files.
[HOST2] ~ % mkdir /tmp/amh && cd /tmp/amh
[HOST2] /tmp/amh % /nfs/src/amhello-1.0/configure --prefix /usr
...
[HOST2] /tmp/amh % make && sudo make install-exec
...
In packages that have installation checks, it would make sense to run make installcheck
(see Section 2.2.1 [Basic Installation], page 3) to verify that the package works correctly
despite the apparent partial installation.
Chapter 2: An Introduction to the Autotools 9
2.2.8 Cross-Compilation
To cross-compile is to build on one platform a binary that will run on another platform.
When speaking of cross-compilation, it is important to distinguish between the build plat-
form on which the compilation is performed, and the host platform on which the resulting
executable is expected to run. The following configure options are used to specify each of
them:
--build=BUILD
The system on which the package is built.
--host=HOST
The system where built programs and libraries will run.
When the --host is used, configure will search for the cross-compiling suite for
this platform. Cross-compilation tools commonly have their target architecture as prefix
of their name. For instance my cross-compiler for MinGW32 has its binaries called
i586-mingw32msvc-gcc, i586-mingw32msvc-ld, i586-mingw32msvc-as, etc.
Here is how we could build amhello-1.0 for i586-mingw32msvc on a GNU/Linux PC.
~/amhello-1.0 % ./configure --build i686-pc-linux-gnu --host i586-mingw32msvc
checking for a BSD-compatible install... /usr/bin/install -c
checking whether build environment is sane... yes
checking for gawk... gawk
checking whether make sets $(MAKE)... yes
checking for i586-mingw32msvc-strip... i586-mingw32msvc-strip
checking for i586-mingw32msvc-gcc... i586-mingw32msvc-gcc
checking for C compiler default output file name... a.exe
checking whether the C compiler works... yes
checking whether we are cross compiling... yes
checking for suffix of executables... .exe
checking for suffix of object files... o
checking whether we are using the GNU C compiler... yes
checking whether i586-mingw32msvc-gcc accepts -g... yes
checking for i586-mingw32msvc-gcc option to accept ANSI C...
...
~/amhello-1.0 % make
...
~/amhello-1.0 % cd src; file hello.exe
hello.exe: MS Windows PE 32-bit Intel 80386 console executable not relocatable
The --host and --build options are usually all we need for cross-compiling. The only
exception is if the package being built is itself a cross-compiler: we need a third option to
specify its target architecture.
--target=TARGET
When building compiler tools: the system for which the tools will create out-
put.
For instance when installing GCC, the GNU Compiler Collection, we can use
--target=TARGET to specify that we want to build GCC as a cross-compiler for TARGET.
Mixing --build and --target, we can actually cross-compile a cross-compiler; such a
three-way cross-compilation is known as a Canadian cross.
See Section “Specifying the System Type” in The Autoconf Manual, for more information
about these configure options.
Chapter 2: An Introduction to the Autotools 10
2.2.9 Renaming Programs at Install Time
The GNU Build System provides means to automatically rename executables and man-
pages before they are installed (see Section 11.2 [Man pages], page 90). This is especially
convenient when installing a GNU package on a system that already has a proprietary im-
plementation you do not want to overwrite. For instance, you may want to install GNU
tar as gtar so you can distinguish it from your vendor’s tar.
This can be done using one of these three configure options.
--program-prefix=PREFIX
Prepend PREFIX to installed program names.
--program-suffix=SUFFIX
Append SUFFIX to installed program names.
--program-transform-name=PROGRAM
Run sed PROGRAM on installed program names.
The following commands would install hello as /usr/local/bin/test-hello, for in-
stance.
~/amhello-1.0 % ./configure --program-prefix test-
...
~/amhello-1.0 % make
...
~/amhello-1.0 % sudo make install
...
2.2.10 Building Binary Packages Using DESTDIR
The GNU Build System’s make install and make uninstall interface does not exactly fit
the needs of a system administrator who has to deploy and upgrade packages on lots of
hosts. In other words, the GNU Build System does not replace a package manager.
Such package managers usually need to know which files have been installed by a package,
so a mere make install is inappropriate.
The DESTDIR variable can be used to perform a staged installation. The package should
be configured as if it was going to be installed in its final location (e.g., --prefix /usr), but
when running make install, the DESTDIR should be set to the absolute name of a directory
into which the installation will be diverted. From this directory it is easy to review which
files are being installed where, and finally copy them to their final location by some means.
For instance here is how we could create a binary package containing a snapshot of all
the files to be installed.
~/amhello-1.0 % ./configure --prefix /usr
...
~/amhello-1.0 % make
...
~/amhello-1.0 % make DESTDIR=$HOME/inst install
...
~/amhello-1.0 % cd ~/inst
~/inst % find . -type f -print > ../files.lst
Chapter 2: An Introduction to the Autotools 11
~/inst % tar zcvf ~/amhello-1.0-i686.tar.gz ‘cat ../file.lst‘
./usr/bin/hello
./usr/share/doc/amhello/README
After this example, amhello-1.0-i686.tar.gz is ready to be uncompressed in / on
many hosts. (Using ‘cat ../file.lst‘ instead of ‘.’ as argument for tar avoids entries
for each subdirectory in the archive: we would not like tar to restore the modification time
of /, /usr/, etc.)
Note that when building packages for several architectures, it might be convenient to use
make install-data and make install-exec (see Section 2.2.7 [Two-Part Install], page 8)
to gather architecture-independent files in a single package.
See Chapter 12 [Install], page 91, for more information.
2.2.11 Preparing Distributions
We have already mentioned make dist. This target collects all your source files and the
necessary parts of the build system to create a tarball named package-version.tar.gz.
Another, more useful command is make distcheck. The distcheck target constructs
package-version.tar.gz just as well as dist, but it additionally ensures most of the use
cases presented so far work:
• It attempts a full compilation of the package (see Section 2.2.1 [Basic Installation],
page 3), unpacking the newly constructed tarball, running make, make check, make
install, as well as make installcheck, and even make dist,
• it tests VPATH builds with read-only source tree (see Section 2.2.6 [VPATH Builds],
page 6),
• it makes sure make clean, make distclean, and make uninstall do not omit any file
(see Section 2.2.2 [Standard Targets], page 4),
• and it checks that DESTDIR installations work (see Section 2.2.10 [DESTDIR], page 10).
All of these actions are performed in a temporary subdirectory, so that no root privileges
are required.
Releasing a package that fails make distcheck means that one of the scenarios we pre-
sented will not work and some users will be disappointed. Therefore it is a good practice
to release a package only after a successful make distcheck. This of course does not imply
that the package will be flawless, but at least it will prevent some of the embarrassing errors
you may find in packages released by people who have never heard about distcheck (like
DESTDIR not working because of a typo, or a distributed file being erased by make clean,
or even VPATH builds not working).
See Section 2.4.1 [Creating amhello], page 13, to recreate amhello-1.0.tar.gz using
make distcheck. See Chapter 14 [Dist], page 93, for more information about distcheck.
2.2.12 Automatic Dependency Tracking
Dependency tracking is performed as a side-effect of compilation. Each time the build
system compiles a source file, it computes its list of dependencies (in C these are the header
files included by the source being compiled). Later, any time make is run and a dependency
appears to have changed, the dependent files will be rebuilt.
Chapter 2: An Introduction to the Autotools 12
When configure is executed, you can see it probing each compiler for the dependency
mechanism it supports (several mechanisms can be used):
~/amhello-1.0 % ./configure --prefix /usr
...
checking dependency style of gcc... gcc3
...
Because dependencies are only computed as a side-effect of the compilation, no depen-
dency information exists the first time a package is built. This is OK because all the files
need to be built anyway: make does not have to decide which files need to be rebuilt. In
fact, dependency tracking is completely useless for one-time builds and there is a configure
option to disable this:
--disable-dependency-tracking
Speed up one-time builds.
Some compilers do not offer any practical way to derive the list of dependencies as a side-
effect of the compilation, requiring a separate run (maybe of another tool) to compute these
dependencies. The performance penalty implied by these methods is important enough to
disable them by default. The option --enable-dependency-tracking must be passed to
configure to activate them.
--enable-dependency-tracking
Do not reject slow dependency extractors.
See Section 28.2 [Dependency Tracking Evolution], page 143, for some discussion about
the different dependency tracking schemes used by Automake over the years.
2.2.13 Nested Packages
Although nesting packages isn’t something we would recommend to someone who is dis-
covering the Autotools, it is a nice feature worthy of mention in this small advertising
tour.
Autoconfiscated packages (that means packages whose build system have been created
by Autoconf and friends) can be nested to arbitrary depth.
A typical setup is that package A will distribute one of the libraries it needs in a sub-
directory. This library B is a complete package with its own GNU Build System. The
configure script of A will run the configure script of B as part of its execution, build-
ing and installing A will also build and install B. Generating a distribution for A will also
include B.
It is possible to gather several package like this. GCC is a heavy user of this feature. This
gives installers a single package to configure, build and install, while it allows developers to
work on subpackages independently.
When configuring nested packages, the configure options given to the top-level
configure are passed recursively to nested configures. A package that does not
understand an option will ignore it, assuming it is meaningful to some other package.
The command configure --help=recursive can be used to display the options sup-
ported by all the included packages.
See Section 7.4 [Subpackages], page 49, for an example setup.
Chapter 2: An Introduction to the Autotools 13
2.3 How Autotools Help
There are several reasons why you may not want to implement the GNU Build System
yourself (read: write a configure script and Makefiles yourself).
• As we have seen, the GNU Build System has a lot of features (see Section 2.2 [Use
Cases], page 2). Some users may expect features you have not implemented because
you did not need them.
• Implementing these features portably is difficult and exhausting. Think of writing
portable shell scripts, and portable Makefiles, for systems you may not have handy.
See Section “Portable Shell Programming” in The Autoconf Manual, to convince your-
self.
• You will have to upgrade your setup to follow changes to the GNU Coding Standards.
The GNU Autotools take all this burden off your back and provide:
• Tools to create a portable, complete, and self-contained GNU Build System, from simple
instructions. Self-contained meaning the resulting build system does not require the
GNU Autotools.
• A central place where fixes and improvements are made: a bug-fix for a portability
issue will benefit every package.
Yet there also exist reasons why you may want NOT to use the Autotools. . . For instance
you may be already using (or used to) another incompatible build system. Autotools will
only be useful if you do accept the concepts of the GNU Build System. People who have
their own idea of how a build system should work will feel frustrated by the Autotools.
2.4 A Small Hello World
In this section we recreate the amhello-1.0 package from scratch. The first subsection
shows how to call the Autotools to instantiate the GNU Build System, while the second
explains the meaning of the configure.ac and Makefile.am files read by the Autotools.
2.4.1 Creating amhello-1.0.tar.gz
Here is how we can recreate amhello-1.0.tar.gz from scratch. The package is simple
enough so that we will only need to write 5 files. (You may copy them from the final
amhello-1.0.tar.gz that is distributed with Automake if you do not want to write them.)
Create the following files in an empty directory.
• src/main.c is the source file for the hello program. We store it in the src/ subdi-
rectory, because later, when the package evolves, it will ease the addition of a man/
directory for man pages, a data/ directory for data files, etc.
~/amhello % cat src/main.c
#include <config.h>
#include <stdio.h>
int
main (void)
{
puts ("Hello World!");
Chapter 2: An Introduction to the Autotools 14
puts ("This is " PACKAGE_STRING ".");
return 0;
}
• README contains some very limited documentation for our little package.
~/amhello % cat README
This is a demonstration package for GNU Automake.
Type ‘info Automake’ to read the Automake manual.
• Makefile.am and src/Makefile.am contain Automake instructions for these two di-
rectories.
~/amhello % cat src/Makefile.am
bin_PROGRAMS = hello
hello_SOURCES = main.c
~/amhello % cat Makefile.am
SUBDIRS = src
dist_doc_DATA = README
• Finally, configure.ac contains Autoconf instructions to create the configure script.
~/amhello % cat configure.ac
AC_INIT([amhello], [1.0], [bug-automake@gnu.org])
AM_INIT_AUTOMAKE([-Wall -Werror foreign])
AC_PROG_CC
AC_CONFIG_HEADERS([config.h])
AC_CONFIG_FILES([
Makefile
src/Makefile
])
AC_OUTPUT
Once you have these five files, it is time to run the Autotools to instantiate the build
system. Do this using the autoreconf command as follows:
~/amhello % autoreconf --install
configure.ac: installing ‘./install-sh’
configure.ac: installing ‘./missing’
src/Makefile.am: installing ‘./depcomp’
At this point the build system is complete.
In addition to the three scripts mentioned in its output, you can see that autoreconf
created four other files: configure, config.h.in, Makefile.in, and src/Makefile.in.
The latter three files are templates that will be adapted to the system by configure under
the names config.h, Makefile, and src/Makefile. Let’s do this:
~/amhello % ./configure
checking for a BSD-compatible install... /usr/bin/install -c
checking whether build environment is sane... yes
checking for gawk... no
checking for mawk... mawk
checking whether make sets $(MAKE)... yes
checking for gcc... gcc
Chapter 2: An Introduction to the Autotools 15
checking for C compiler default output file name... a.out
checking whether the C compiler works... yes
checking whether we are cross compiling... no
checking for suffix of executables...
checking for suffix of object files... o
checking whether we are using the GNU C compiler... yes
checking whether gcc accepts -g... yes
checking for gcc option to accept ISO C89... none needed
checking for style of include used by make... GNU
checking dependency style of gcc... gcc3
configure: creating ./config.status
config.status: creating Makefile
config.status: creating src/Makefile
config.status: creating config.h
config.status: executing depfiles commands
You can see Makefile, src/Makefile, and config.h being created at the end after
configure has probed the system. It is now possible to run all the targets we wish (see
Section 2.2.2 [Standard Targets], page 4). For instance:
~/amhello % make
...
~/amhello % src/hello
Hello World!
This is amhello 1.0.
~/amhello % make distcheck
...
=============================================
amhello-1.0 archives ready for distribution:
amhello-1.0.tar.gz
=============================================
Note that running autoreconf is only needed initially when the GNU Build System does
not exist. When you later change some instructions in a Makefile.am or configure.ac,
the relevant part of the build system will be regenerated automatically when you execute
make.
autoreconf is a script that calls autoconf, automake, and a bunch of other commands
in the right order. If you are beginning with these tools, it is not important to figure out
in which order all these tools should be invoked and why. However, because Autoconf and
Automake have separate manuals, the important point to understand is that autoconf is in
charge of creating configure from configure.ac, while automake is in charge of creating
Makefile.ins from Makefile.ams and configure.ac. This should at least direct you to
the right manual when seeking answers.
2.4.2 amhello-1.0 Explained
Let us begin with the contents of configure.ac.
AC_INIT([amhello], [1.0], [bug-automake@gnu.org])
AM_INIT_AUTOMAKE([-Wall -Werror foreign])
AC_PROG_CC
Chapter 2: An Introduction to the Autotools 16
AC_CONFIG_HEADERS([config.h])
AC_CONFIG_FILES([
Makefile
src/Makefile
])
AC_OUTPUT
This file is read by both autoconf (to create configure) and automake (to create the
various Makefile.ins). It contains a series of M4 macros that will be expanded as shell code
to finally form the configure script. We will not elaborate on the syntax of this file, because
the Autoconf manual has a whole section about it (see Section “Writing configure.ac” in
The Autoconf Manual).
The macros prefixed with AC_ are Autoconf macros, documented in the Autoconf manual
(see Section “Autoconf Macro Index” in The Autoconf Manual). The macros that start with
AM_ are Automake macros, documented later in this manual (see Section B.1 [Macro Index],
page 157).
The first two lines of configure.ac initialize Autoconf and Automake. AC_INIT takes
in as parameters the name of the package, its version number, and a contact address for
bug-reports about the package (this address is output at the end of ./configure --help,
for instance). When adapting this setup to your own package, by all means please do not
blindly copy Automake’s address: use the mailing list of your package, or your own mail
address.
The argument to AM_INIT_AUTOMAKE is a list of options for automake (see Chapter 17
[Options], page 99). -Wall and -Werror ask automake to turn on all warnings and report
them as errors. We are speaking of Automake warnings here, such as dubious instructions in
Makefile.am. This has absolutely nothing to do with how the compiler will be called, even
though it may support options with similar names. Using -Wall -Werror is a safe setting
when starting to work on a package: you do not want to miss any issues. Later you may
decide to relax things a bit. The foreign option tells Automake that this package will not
follow the GNU Standards. GNU packages should always distribute additional files such as
ChangeLog, AUTHORS, etc. We do not want automake to complain about these missing files
in our small example.
The AC_PROG_CC line causes the configure script to search for a C compiler and
define the variable CC with its name. The src/Makefile.in file generated by Automake
uses the variable CC to build hello, so when configure creates src/Makefile from
src/Makefile.in, it will define CC with the value it has found. If Automake is asked to
create a Makefile.in that uses CC but configure.ac does not define it, it will suggest
you add a call to AC_PROG_CC.
The AC_CONFIG_HEADERS([config.h]) invocation causes the configure script to create
a config.h file gathering ‘#define’s defined by other macros in configure.ac. In our case,
the AC_INIT macro already defined a few of them. Here is an excerpt of config.h after
configure has run:
...
/* Define to the address where bug reports for this package should be sent. */
#define PACKAGE_BUGREPORT "bug-automake@gnu.org"
/* Define to the full name and version of this package. */
Chapter 2: An Introduction to the Autotools 17
#define PACKAGE_STRING "amhello 1.0"
...
As you probably noticed, src/main.c includes config.h so it can use PACKAGE_STRING.
In a real-world project, config.h can grow really big, with one ‘#define’ per feature probed
on the system.
The AC_CONFIG_FILES macro declares the list of files that configure should create from
their *.in templates. Automake also scans this list to find the Makefile.am files it must
process. (This is important to remember: when adding a new directory to your project,
you should add its Makefile to this list, otherwise Automake will never process the new
Makefile.am you wrote in that directory.)
Finally, the AC_OUTPUT line is a closing command that actually produces the part of the
script in charge of creating the files registered with AC_CONFIG_HEADERS and AC_CONFIG_
FILES.
When starting a new project, we suggest you start with such a simple configure.ac, and
gradually add the other tests it requires. The command autoscan can also suggest a few of
the tests your package may need (see Section “Using autoscan to Create configure.ac”
in The Autoconf Manual).
We now turn to src/Makefile.am. This file contains Automake instructions to build
and install hello.
bin_PROGRAMS = hello
hello_SOURCES = main.c
A Makefile.am has the same syntax as an ordinary Makefile. When automake processes
a Makefile.am it copies the entire file into the output Makefile.in (that will be later turned
into Makefile by configure) but will react to certain variable definitions by generating
some build rules and other variables. Often Makefile.ams contain only a list of variable
definitions as above, but they can also contain other variable and rule definitions that
automake will pass along without interpretation.
Variables that end with _PROGRAMS are special variables that list programs that the
resulting Makefile should build. In Automake speak, this _PROGRAMS suffix is called a
primary; Automake recognizes other primaries such as _SCRIPTS, _DATA, _LIBRARIES, etc.
corresponding to different types of files.
The ‘bin’ part of the bin_PROGRAMS tells automake that the resulting programs should
be installed in bindir. Recall that the GNU Build System uses a set of variables to denote
destination directories and allow users to customize these locations (see Section 2.2.3 [Stan-
dard Directory Variables], page 4). Any such directory variable can be put in front of a
primary (omitting the dir suffix) to tell automake where to install the listed files.
Programs need to be built from source files, so for each program prog listed in a
_PROGRAMS variable, automake will look for another variable named prog_SOURCES list-
ing its source files. There may be more than one source file: they will all be compiled and
linked together.
Automake also knows that source files need to be distributed when creating a tarball
(unlike built programs). So a side-effect of this hello_SOURCES declaration is that main.c
will be part of the tarball created by make dist.
Finally here are some explanations regarding the top-level Makefile.am.
SUBDIRS = src
Chapter 3: General ideas 18
dist_doc_DATA = README
SUBDIRS is a special variable listing all directories that make should recurse into before
processing the current directory. So this line is responsible for make building src/hello
even though we run it from the top-level. This line also causes make install to install
src/hello before installing README (not that this order matters).
The line dist_doc_DATA = README causes README to be distributed and installed in
docdir. Files listed with the _DATA primary are not automatically part of the tarball built
with make dist, so we add the dist_ prefix so they get distributed. However, for README it
would not have been necessary: automake automatically distributes any README file it en-
counters (the list of other files automatically distributed is presented by automake --help).
The only important effect of this second line is therefore to install README during make
install.
3 General ideas
The following sections cover a few basic ideas that will help you understand how Automake
works.
3.1 General Operation
Automake works by reading a Makefile.am and generating a Makefile.in. Certain vari-
ables and rules defined in the Makefile.am instruct Automake to generate more specialized
code; for instance, a bin_PROGRAMS variable definition will cause rules for compiling and
linking programs to be generated.
The variable definitions and rules in the Makefile.am are copied verbatim into the
generated file. This allows you to add arbitrary code into the generated Makefile.in. For
instance, the Automake distribution includes a non-standard rule for the git-dist target,
which the Automake maintainer uses to make distributions from his source control system.
Note that most GNU make extensions are not recognized by Automake. Using such
extensions in a Makefile.am will lead to errors or confusing behavior.
A special exception is that the GNU make append operator, ‘+=’, is supported. This
operator appends its right hand argument to the variable specified on the left. Automake
will translate the operator into an ordinary ‘=’ operator; ‘+=’ will thus work with any make
program.
Automake tries to keep comments grouped with any adjoining rules or variable defini-
tions.
A rule defined in Makefile.am generally overrides any such rule of a similar name that
would be automatically generated by automake. Although this is a supported feature,
it is generally best to avoid making use of it, as sometimes the generated rules are very
particular.
Similarly, a variable defined in Makefile.am or AC_SUBSTed from configure.ac will
override any definition of the variable that automake would ordinarily create. This feature
is more often useful than the ability to override a rule. Be warned that many of the variables
generated by automake are considered to be for internal use only, and their names might
change in future releases.
Chapter 3: General ideas 19
When examining a variable definition, Automake will recursively examine variables refer-
enced in the definition. For example, if Automake is looking at the content of foo_SOURCES
in this snippet
xs = a.c b.c
foo_SOURCES = c.c $(xs)
it would use the files a.c, b.c, and c.c as the contents of foo_SOURCES.
Automake also allows a form of comment that is not copied into the output; all lines
beginning with ‘##’ (leading spaces allowed) are completely ignored by Automake.
It is customary to make the first line of Makefile.am read:
## Process this file with automake to produce Makefile.in
3.2 Strictness
While Automake is intended to be used by maintainers of GNU packages, it does make
some effort to accommodate those who wish to use it, but do not want to use all the GNU
conventions.
To this end, Automake supports three levels of strictness—the strictness indicating how
stringently Automake should check standards conformance.
The valid strictness levels are:
foreign Automake will check for only those things that are absolutely required for proper
operations. For instance, whereas GNU standards dictate the existence of a
NEWS file, it will not be required in this mode. The name comes from the fact
that Automake is intended to be used for GNU programs; these relaxed rules
are not the standard mode of operation.
gnu Automake will check—as much as possible—for compliance to the GNU stan-
dards for packages. This is the default.
gnits Automake will check for compliance to the as-yet-unwritten Gnits standards.
These are based on the GNU standards, but are even more detailed. Unless
you are a Gnits standards contributor, it is recommended that you avoid this
option until such time as the Gnits standard is actually published (which may
never happen).
See Chapter 21 [Gnits], page 107, for more information on the precise implications of
the strictness level.
Automake also has a special “cygnus” mode that is similar to strictness but handled
differently. This mode is useful for packages that are put into a “Cygnus” style tree (e.g.,
the GCC tree). See Chapter 22 [Cygnus], page 108, for more information on this mode.
3.3 The Uniform Naming Scheme
Automake variables generally follow a uniform naming scheme that makes it easy to decide
how programs (and other derived objects) are built, and how they are installed. This scheme
also supports configure time determination of what should be built.
At make time, certain variables are used to determine which objects are to be built. The
variable names are made of several pieces that are concatenated together.
Chapter 3: General ideas 20
The piece that tells automake what is being built is commonly called the primary. For
instance, the primary PROGRAMS holds a list of programs that are to be compiled and linked.
A different set of names is used to decide where the built objects should be installed.
These names are prefixes to the primary, and they indicate which standard directory should
be used as the installation directory. The standard directory names are given in the GNU
standards (see Section “Directory Variables” in The GNU Coding Standards). Automake
extends this list with pkgdatadir, pkgincludedir, pkglibdir, and pkglibexecdir; these
are the same as the non-‘pkg’ versions, but with ‘$(PACKAGE)’ appended. For instance,
pkglibdir is defined as ‘$(libdir)/$(PACKAGE)’.
For each primary, there is one additional variable named by prepending ‘EXTRA_’ to the
primary name. This variable is used to list objects that may or may not be built, depending
on what configure decides. This variable is required because Automake must statically
know the entire list of objects that may be built in order to generate a Makefile.in that
will work in all cases.
For instance, cpio decides at configure time which programs should be built. Some of
the programs are installed in bindir, and some are installed in sbindir:
EXTRA_PROGRAMS = mt rmt
bin_PROGRAMS = cpio pax
sbin_PROGRAMS = $(MORE_PROGRAMS)
Defining a primary without a prefix as a variable, e.g., ‘PROGRAMS’, is an error.
Note that the common ‘dir’ suffix is left off when constructing the variable names; thus
one writes ‘bin_PROGRAMS’ and not ‘bindir_PROGRAMS’.
Not every sort of object can be installed in every directory. Automake will flag those
attempts it finds in error. Automake will also diagnose obvious misspellings in directory
names.
Sometimes the standard directories—even as augmented by Automake—are not enough.
In particular it is sometimes useful, for clarity, to install objects in a subdirectory of some
predefined directory. To this end, Automake allows you to extend the list of possible
installation directories. A given prefix (e.g., ‘zar’) is valid if a variable of the same name
with ‘dir’ appended is defined (e.g., ‘zardir’).
For instance, the following snippet will install file.xml into ‘$(datadir)/xml’.
xmldir = $(datadir)/xml
xml_DATA = file.xml
The special prefix ‘noinst_’ indicates that the objects in question should be built but not
installed at all. This is usually used for objects required to build the rest of your package,
for instance static libraries (see Section 8.2 [A Library], page 55), or helper scripts.
The special prefix ‘check_’ indicates that the objects in question should not be built
until the ‘make check’ command is run. Those objects are not installed either.
The current primary names are ‘PROGRAMS’, ‘LIBRARIES’, ‘LISP’, ‘PYTHON’, ‘JAVA’,
‘SCRIPTS’, ‘DATA’, ‘HEADERS’, ‘MANS’, and ‘TEXINFOS’.
Some primaries also allow additional prefixes that control other aspects of automake’s
behavior. The currently defined prefixes are ‘dist_’, ‘nodist_’, ‘nobase_’, and ‘notrans_’.
Chapter 3: General ideas 21
These prefixes are explained later (see Section 8.4 [Program and Library Variables], page 62)
(see Section 11.2 [Man pages], page 90).
3.4 How derived variables are named
Sometimes a Makefile variable name is derived from some text the maintainer supplies. For
instance, a program name listed in ‘_PROGRAMS’ is rewritten into the name of a ‘_SOURCES’
variable. In cases like this, Automake canonicalizes the text, so that program names and
the like do not have to follow Makefile variable naming rules. All characters in the name
except for letters, numbers, the strudel (@), and the underscore are turned into underscores
when making variable references.
For example, if your program is named sniff-glue, the derived variable name would
be ‘sniff_glue_SOURCES’, not ‘sniff-glue_SOURCES’. Similarly the sources for a library
named libmumble++.a should be listed in the ‘libmumble___a_SOURCES’ variable.
The strudel is an addition, to make the use of Autoconf substitutions in variable names
less obfuscating.
3.5 Variables reserved for the user
Some Makefile variables are reserved by the GNU Coding Standards for the use of the
“user”—the person building the package. For instance, CFLAGS is one such variable.
Sometimes package developers are tempted to set user variables such as CFLAGS because
it appears to make their job easier. However, the package itself should never set a user
variable, particularly not to include switches that are required for proper compilation of
the package. Since these variables are documented as being for the package builder, that
person rightfully expects to be able to override any of these variables at build time.
To get around this problem, Automake introduces an automake-specific shadow variable
for each user flag variable. (Shadow variables are not introduced for variables like CC, where
they would make no sense.) The shadow variable is named by prepending ‘AM_’ to the user
variable’s name. For instance, the shadow variable for YFLAGS is AM_YFLAGS. The package
maintainer—that is, the author(s) of the Makefile.am and configure.ac files—may adjust
these shadow variables however necessary.
See Section 27.6 [Flag Variables Ordering], page 121, for more discussion about these
variables and how they interact with per-target variables.
3.6 Programs automake might require
Automake sometimes requires helper programs so that the generated Makefile can do its
work properly. There are a fairly large number of them, and we list them here.
Although all of these files are distributed and installed with Automake, a couple of them
are maintained separately. The Automake copies are updated before each release, but we
mention the original source in case you need more recent versions.
ansi2knr.c
ansi2knr.1
These two files are used for de-ANSI-fication support (obsolete see Section 8.17
[ANSI], page 76).
Chapter 3: General ideas 22
compile This is a wrapper for compilers that do not accept options -c and -o at the
same time. It is only used when absolutely required. Such compilers are rare.
config.guess
config.sub
These two programs compute the canonical triplets for the given build, host, or
target architecture. These programs are updated regularly to support new ar-
chitectures and fix probes broken by changes in new kernel versions. Each new
release of Automake comes with up-to-date copies of these programs. If your
copy of Automake is getting old, you are encouraged to fetch the latest ver-
sions of these files from http://savannah.gnu.org/git/?group=config be-
fore making a release.
config-ml.in
This file is not a program, it is a configure fragment used for multilib support
(see Section 18.3 [Multilibs], page 104). This file is maintained in the GCC tree
at http://gcc.gnu.org/svn.html.
depcomp This program understands how to run a compiler so that it will generate not
only the desired output but also dependency information that is then used by
the automatic dependency tracking feature (see Section 8.18 [Dependencies],
page 77).
elisp-comp
This program is used to byte-compile Emacs Lisp code.
install-sh
This is a replacement for the install program that works on platforms where
install is unavailable or unusable.
mdate-sh This script is used to generate a version.texi file. It examines a file and prints
some date information about it.
missing This wraps a number of programs that are typically only required by maintain-
ers. If the program in question doesn’t exist, missing prints an informative
warning and attempts to fix things so that the build can continue.
mkinstalldirs
This script used to be a wrapper around ‘mkdir -p’, which is not portable. Now
we prefer to use ‘install-sh -d’ when configure finds that ‘mkdir -p’ does not
work, this makes one less script to distribute.
For backward compatibility mkinstalldirs is still used and distributed when
automake finds it in a package. But it is no longer installed automatically, and
it should be safe to remove it.
py-compile
This is used to byte-compile Python scripts.
symlink-tree
This program duplicates a tree of directories, using symbolic links instead of
copying files. Such an operation is performed when building multilibs (see
Section 18.3 [Multilibs], page 104). This file is maintained in the GCC tree at
http://gcc.gnu.org/svn.html.
Chapter 4: Some example packages 23
texinfo.tex
Not a program, this file is required for ‘make dvi’, ‘make ps’ and ‘make pdf’
to work when Texinfo sources are in the package. The latest version can be
downloaded from http://www.gnu.org/software/texinfo/.
ylwrap This program wraps lex and yacc to rename their output files. It also ensures
that, for instance, multiple yacc instances can be invoked in a single directory
in parallel.
4 Some example packages
This section contains two small examples.
The first example (see Section 4.1 [Complete], page 23) assumes you have an existing
project already using Autoconf, with handcrafted Makefiles, and that you want to convert
it to using Automake. If you are discovering both tools, it is probably better that you look
at the Hello World example presented earlier (see Section 2.4 [Hello World], page 13).
The second example (see Section 4.2 [true], page 24) shows how two programs can be
built from the same file, using different compilation parameters. It contains some technical
digressions that are probably best skipped on first read.
4.1 A simple example, start to finish
Let’s suppose you just finished writing zardoz, a program to make your head float from
vortex to vortex. You’ve been using Autoconf to provide a portability framework, but
your Makefile.ins have been ad-hoc. You want to make them bulletproof, so you turn to
Automake.
The first step is to update your configure.ac to include the commands that automake
needs. The way to do this is to add an AM_INIT_AUTOMAKE call just after AC_INIT:
AC_INIT([zardoz], [1.0])
AM_INIT_AUTOMAKE
...
Since your program doesn’t have any complicating factors (e.g., it doesn’t use gettext,
it doesn’t want to build a shared library), you’re done with this part. That was easy!
Now you must regenerate configure. But to do that, you’ll need to tell autoconf how
to find the new macro you’ve used. The easiest way to do this is to use the aclocal program
to generate your aclocal.m4 for you. But wait. . . maybe you already have an aclocal.m4,
because you had to write some hairy macros for your program. The aclocal program lets
you put your own macros into acinclude.m4, so simply rename and then run:
mv aclocal.m4 acinclude.m4
aclocal
autoconf
Now it is time to write your Makefile.am for zardoz. Since zardoz is a user program,
you want to install it where the rest of the user programs go: bindir. Additionally, zardoz
has some Texinfo documentation. Your configure.ac script uses AC_REPLACE_FUNCS, so
you need to link against ‘$(LIBOBJS)’. So here’s what you’d write:
bin_PROGRAMS = zardoz
Chapter 4: Some example packages 24
zardoz_SOURCES = main.c head.c float.c vortex9.c gun.c
zardoz_LDADD = $(LIBOBJS)
info_TEXINFOS = zardoz.texi
Now you can run ‘automake --add-missing’ to generate your Makefile.in and grab
any auxiliary files you might need, and you’re done!
4.2 Building true and false
Here is another, trickier example. It shows how to generate two programs (true and false)
from the same source file (true.c). The difficult part is that each compilation of true.c
requires different cpp flags.
bin_PROGRAMS = true false
false_SOURCES =
false_LDADD = false.o
true.o: true.c
$(COMPILE) -DEXIT_CODE=0 -c true.c
false.o: true.c
$(COMPILE) -DEXIT_CODE=1 -o false.o -c true.c
Note that there is no true_SOURCES definition. Automake will implicitly assume that
there is a source file named true.c (see Section 8.5 [Default SOURCES], page 65), and
define rules to compile true.o and link true. The ‘true.o: true.c’ rule supplied by the
above Makefile.am, will override the Automake generated rule to build true.o.
false_SOURCES is defined to be empty—that way no implicit value is substituted. Be-
cause we have not listed the source of false, we have to tell Automake how to link the
program. This is the purpose of the false_LDADD line. A false_DEPENDENCIES variable,
holding the dependencies of the false target will be automatically generated by Automake
from the content of false_LDADD.
The above rules won’t work if your compiler doesn’t accept both -c and -o. The simplest
fix for this is to introduce a bogus dependency (to avoid problems with a parallel make):
true.o: true.c false.o
$(COMPILE) -DEXIT_CODE=0 -c true.c
false.o: true.c
$(COMPILE) -DEXIT_CODE=1 -c true.c && mv true.o false.o
Also, these explicit rules do not work if the obsolete de-ANSI-fication feature is used (see
Section 8.17 [ANSI], page 76). Supporting de-ANSI-fication requires a little more work:
true_.o: true_.c false_.o
$(COMPILE) -DEXIT_CODE=0 -c true_.c
false_.o: true_.c
$(COMPILE) -DEXIT_CODE=1 -c true_.c && mv true_.o false_.o
As it turns out, there is also a much easier way to do this same task. Some of the above
techniques are useful enough that we’ve kept the example in the manual. However if you
Chapter 5: Creating a Makefile.in 25
were to build true and false in real life, you would probably use per-program compilation
flags, like so:
bin_PROGRAMS = false true
false_SOURCES = true.c
false_CPPFLAGS = -DEXIT_CODE=1
true_SOURCES = true.c
true_CPPFLAGS = -DEXIT_CODE=0
In this case Automake will cause true.c to be compiled twice, with different flags. De-
ANSI-fication will work automatically. In this instance, the names of the object files would
be chosen by automake; they would be false-true.o and true-true.o. (The name of the
object files rarely matters.)
5 Creating a Makefile.in
To create all the Makefile.ins for a package, run the automake program in the top
level directory, with no arguments. automake will automatically find each appropriate
Makefile.am (by scanning configure.ac; see Chapter 6 [configure], page 28) and generate
the corresponding Makefile.in. Note that automake has a rather simplistic view of what
constitutes a package; it assumes that a package has only one configure.ac, at the top. If
your package has multiple configure.acs, then you must run automake in each directory
holding a configure.ac. (Alternatively, you may rely on Autoconf’s autoreconf, which
is able to recurse your package tree and run automake where appropriate.)
You can optionally give automake an argument; .am is appended to the argument and
the result is used as the name of the input file. This feature is generally only used to
automatically rebuild an out-of-date Makefile.in. Note that automake must always be run
from the topmost directory of a project, even if being used to regenerate the Makefile.in
in some subdirectory. This is necessary because automake must scan configure.ac, and
because automake uses the knowledge that a Makefile.in is in a subdirectory to change
its behavior in some cases.
Automake will run autoconf to scan configure.ac and its dependencies (i.e.,
aclocal.m4 and any included file), therefore autoconf must be in your PATH. If there
is an AUTOCONF variable in your environment it will be used instead of autoconf, this
allows you to select a particular version of Autoconf. By the way, don’t misunderstand
this paragraph: automake runs autoconf to scan your configure.ac, this won’t build
configure and you still have to run autoconf yourself for this purpose.
automake accepts the following options:
-a
--add-missing
Automake requires certain common files to exist in certain situations; for
instance, config.guess is required if configure.ac invokes AC_CANONICAL_
HOST. Automake is distributed with several of these files (see Section 3.6
[Auxiliary Programs], page 21); this option will cause the missing ones to be
automatically added to the package, whenever possible. In general if Automake
Chapter 5: Creating a Makefile.in 26
tells you a file is missing, try using this option. By default Automake tries to
make a symbolic link pointing to its own copy of the missing file; this can be
changed with --copy.
Many of the potentially-missing files are common scripts whose location may be
specified via the AC_CONFIG_AUX_DIR macro. Therefore, AC_CONFIG_AUX_DIR’s
setting affects whether a file is considered missing, and where the missing file
is added (see Section 6.2 [Optional], page 30).
In some strictness modes, additional files are installed, see Chapter 21 [Gnits],
page 107, for more information.
--libdir=dir
Look for Automake data files in directory dir instead of in the installation
directory. This is typically used for debugging.
-c
--copy When used with --add-missing, causes installed files to be copied. The default
is to make a symbolic link.
--cygnus Causes the generated Makefile.ins to follow Cygnus rules, instead of GNU or
Gnits rules. For more information, see Chapter 22 [Cygnus], page 108.
-f
--force-missing
When used with --add-missing, causes standard files to be reinstalled even if
they already exist in the source tree. This involves removing the file from the
source tree before creating the new symlink (or, with --copy, copying the new
file).
--foreign
Set the global strictness to foreign. For more information, see Section 3.2
[Strictness], page 19.
--gnits Set the global strictness to gnits. For more information, see Chapter 21 [Gnits],
page 107.
--gnu Set the global strictness to gnu. For more information, see Chapter 21 [Gnits],
page 107. This is the default strictness.
--help Print a summary of the command line options and exit.
-i
--ignore-deps
This disables the dependency tracking feature in generated Makefiles; see
Section 8.18 [Dependencies], page 77.
--include-deps
This enables the dependency tracking feature. This feature is enabled by de-
fault. This option is provided for historical reasons only and probably should
not be used.
--no-force
Ordinarily automake creates all Makefile.ins mentioned in configure.ac.
This option causes it to only update those Makefile.ins that are out of date
with respect to one of their dependents.
Chapter 5: Creating a Makefile.in 27
-o dir
--output-dir=dir
Put the generated Makefile.in in the directory dir. Ordinarily each
Makefile.in is created in the directory of the corresponding Makefile.am.
This option is deprecated and will be removed in a future release.
-v
--verbose
Cause Automake to print information about which files are being read or cre-
ated.
--version
Print the version number of Automake and exit.
-W CATEGORY
--warnings=category
Output warnings falling in category. category can be one of:
gnu warnings related to the GNU Coding Standards (see The GNU
Coding Standards).
obsolete obsolete features or constructions
override user redefinitions of Automake rules or variables
portability
portability issues (e.g., use of make features that are known to be
not portable)
syntax weird syntax, unused variables, typos
unsupported
unsupported or incomplete features
all all the warnings
none turn off all the warnings
error treat warnings as errors
A category can be turned off by prefixing its name with ‘no-’. For instance,
-Wno-syntax will hide the warnings about unused variables.
The categories output by default are ‘syntax’ and ‘unsupported’. Additionally,
‘gnu’ and ‘portability’ are enabled in --gnu and --gnits strictness.
The environment variable WARNINGS can contain a comma separated list of
categories to enable. It will be taken into account before the command-line
switches, this way -Wnone will also ignore any warning category enabled by
WARNINGS. This variable is also used by other tools like autoconf; unknown
categories are ignored for this reason.
Chapter 6: Scanning configure.ac 28
6 Scanning configure.ac
Automake scans the package’s configure.ac to determine certain information about the
package. Some autoconf macros are required and some variables must be defined in
configure.ac. Automake will also use information from configure.ac to further tailor
its output.
Automake also supplies some Autoconf macros to make the maintenance easier. These
macros can automatically be put into your aclocal.m4 using the aclocal program.
6.1 Configuration requirements
The one real requirement of Automake is that your configure.ac call AM_INIT_AUTOMAKE.
This macro does several things that are required for proper Automake operation (see
Section 6.4 [Macros], page 42).
Here are the other macros that Automake requires but which are not run by AM_INIT_
AUTOMAKE:
AC_CONFIG_FILES
AC_OUTPUT
These two macros are usually invoked as follows near the end of configure.ac.
...
AC_CONFIG_FILES([
Makefile
doc/Makefile
src/Makefile
src/lib/Makefile
...
])
AC_OUTPUT
Automake uses these to determine which files to create (see Section “Creating
Output Files” in The Autoconf Manual). A listed file is considered to be an
Automake generated Makefile if there exists a file with the same name and
the .am extension appended. Typically, ‘AC_CONFIG_FILES([foo/Makefile])’
will cause Automake to generate foo/Makefile.in if foo/Makefile.am exists.
When using AC_CONFIG_FILES with multiple input files, as in
AC_CONFIG_FILES([Makefile:top.in:Makefile.in:bot.in])
automake will generate the first .in input file for which a .am file exists. If no
such file exists the output file is not considered to be generated by Automake.
Files created by AC_CONFIG_FILES, be they Automake Makefiles or not, are all
removed by ‘make distclean’. Their inputs are automatically distributed, un-
less they are the output of prior AC_CONFIG_FILES commands. Finally, rebuild
rules are generated in the Automake Makefile existing in the subdirectory of
the output file, if there is one, or in the top-level Makefile otherwise.
The above machinery (cleaning, distributing, and rebuilding) works fine if the
AC_CONFIG_FILES specifications contain only literals. If part of the specification
Chapter 6: Scanning configure.ac 29
uses shell variables, automake will not be able to fulfill this setup, and you will
have to complete the missing bits by hand. For instance, on
file=input
...
AC_CONFIG_FILES([output:$file],, [file=$file])
automake will output rules to clean output, and rebuild it. However the rebuild
rule will not depend on input, and this file will not be distributed either. (You
must add ‘EXTRA_DIST = input’ to your Makefile.am if input is a source file.)
Similarly
file=output
file2=out:in
...
AC_CONFIG_FILES([$file:input],, [file=$file])
AC_CONFIG_FILES([$file2],, [file2=$file2])
will only cause input to be distributed. No file will be cleaned automatically
(add ‘DISTCLEANFILES = output out’ yourself), and no rebuild rule will be out-
put.
Obviously automake cannot guess what value ‘$file’ is going to hold later when
configure is run, and it cannot use the shell variable ‘$file’ in a Makefile.
However, if you make reference to ‘$file’ as ‘${file}’ (i.e., in a way that
is compatible with make’s syntax) and furthermore use AC_SUBST to ensure
that ‘${file}’ is meaningful in a Makefile, then automake will be able to use
‘${file}’ to generate all these rules. For instance, here is how the Automake
package itself generates versioned scripts for its test suite:
AC_SUBST([APIVERSION], ...)
...
AC_CONFIG_FILES(
[tests/aclocal-${APIVERSION}:tests/aclocal.in],
[chmod +x tests/aclocal-${APIVERSION}],
[APIVERSION=$APIVERSION])
AC_CONFIG_FILES(
[tests/automake-${APIVERSION}:tests/automake.in],
[chmod +x tests/automake-${APIVERSION}])
Here cleaning, distributing, and rebuilding are done automatically, because
‘${APIVERSION}’ is known at make-time.
Note that you should not use shell variables to declare Makefile files for which
automake must create Makefile.in. Even AC_SUBST does not help here, be-
cause automake needs to know the file name when it runs in order to check
whether Makefile.am exists. (In the very hairy case that your setup requires
such use of variables, you will have to tell Automake which Makefile.ins to
generate on the command-line.)
It is possible to let automake emit conditional rules for AC_CONFIG_FILES with
the help of AM_COND_IF (see Section 6.2 [Optional], page 30).
To summarize:
• Use literals for Makefiles, and for other files whenever possible.
Chapter 6: Scanning configure.ac 30
• Use ‘$file’ (or ‘${file}’ without ‘AC_SUBST([file])’) for files that
automake should ignore.
• Use ‘${file}’ and ‘AC_SUBST([file])’ for files that automake should not
ignore.
6.2 Other things Automake recognizes
Every time Automake is run it calls Autoconf to trace configure.ac. This way it can
recognize the use of certain macros and tailor the generated Makefile.in appropriately.
Currently recognized macros and their effects are:
AC_CANONICAL_BUILD
AC_CANONICAL_HOST
AC_CANONICAL_TARGET
Automake will ensure that config.guess and config.sub exist. Also, the
Makefile variables build_triplet, host_triplet and target_triplet are
introduced. See Section “Getting the Canonical System Type” in The Autoconf
Manual.
AC_CONFIG_AUX_DIR
Automake will look for various helper scripts, such as install-sh, in
the directory named in this macro invocation. (The full list of scripts is:
config.guess, config.sub, depcomp, elisp-comp, compile, install-sh,
ltmain.sh, mdate-sh, missing, mkinstalldirs, py-compile, texinfo.tex,
and ylwrap.) Not all scripts are always searched for; some scripts will only be
sought if the generated Makefile.in requires them.
If AC_CONFIG_AUX_DIR is not given, the scripts are looked for in their standard
locations. For mdate-sh, texinfo.tex, and ylwrap, the standard location
is the source directory corresponding to the current Makefile.am. For the
rest, the standard location is the first one of ., .., or ../.. (relative to the
top source directory) that provides any one of the helper scripts. See Section
“Finding ‘configure’ Input” in The Autoconf Manual.
Required files from AC_CONFIG_AUX_DIR are automatically distributed, even if
there is no Makefile.am in this directory.
AC_CONFIG_LIBOBJ_DIR
Automake will require the sources file declared with AC_LIBSOURCE (see below)
in the directory specified by this macro.
AC_CONFIG_HEADERS
Automake will generate rules to rebuild these headers. Older versions of
Automake required the use of AM_CONFIG_HEADER (see Section 6.4 [Macros],
page 42); this is no longer the case.
As for AC_CONFIG_FILES (see Section 6.1 [Requirements], page 28), parts of the
specification using shell variables will be ignored as far as cleaning, distributing,
and rebuilding is concerned.
AC_CONFIG_LINKS
Automake will generate rules to remove configure generated links on ‘make
distclean’ and to distribute named source files as part of ‘make dist’.
Chapter 6: Scanning configure.ac 31
As for AC_CONFIG_FILES (see Section 6.1 [Requirements], page 28), parts of
the specification using shell variables will be ignored as far as cleaning and
distributing is concerned. (There is no rebuild rules for links.)
AC_LIBOBJ
AC_LIBSOURCE
AC_LIBSOURCES
Automake will automatically distribute any file listed in AC_LIBSOURCE or AC_
LIBSOURCES.
Note that the AC_LIBOBJ macro calls AC_LIBSOURCE. So if an Autoconf macro
is documented to call ‘AC_LIBOBJ([file])’, then file.c will be distributed
automatically by Automake. This encompasses many macros like AC_FUNC_
ALLOCA, AC_FUNC_MEMCMP, AC_REPLACE_FUNCS, and others.
By the way, direct assignments to LIBOBJS are no longer supported. You should
always use AC_LIBOBJ for this purpose. See Section “AC_LIBOBJ vs. LIBOBJS”
in The Autoconf Manual.
AC_PROG_RANLIB
This is required if any libraries are built in the package. See Section “Particular
Program Checks” in The Autoconf Manual.
AC_PROG_CXX
This is required if any C++ source is included. See Section “Particular Program
Checks” in The Autoconf Manual.
AC_PROG_OBJC
This is required if any Objective C source is included. See Section “Particular
Program Checks” in The Autoconf Manual.
AC_PROG_F77
This is required if any Fortran 77 source is included. This macro is distributed
with Autoconf version 2.13 and later. See Section “Particular Program Checks”
in The Autoconf Manual.
AC_F77_LIBRARY_LDFLAGS
This is required for programs and shared libraries that are a mixture of lan-
guages that include Fortran 77 (see Section 8.13.3 [Mixing Fortran 77 With C
and C++], page 73). See Section 6.4 [Autoconf macros supplied with Automake],
page 42.
AC_FC_SRCEXT
Automake will add the flags computed by AC_FC_SRCEXT to compilation of files
with the respective source extension (see Section “Fortran Compiler Character-
istics” in The Autoconf Manual).
AC_PROG_FC
This is required if any Fortran 90/95 source is included. This macro is dis-
tributed with Autoconf version 2.58 and later. See Section “Particular Program
Checks” in The Autoconf Manual.
Chapter 6: Scanning configure.ac 32
AC_PROG_LIBTOOL
Automake will turn on processing for libtool (see Section “Introduction” in
The Libtool Manual).
AC_PROG_YACC
If a Yacc source file is seen, then you must either use this macro or define the
variable YACC in configure.ac. The former is preferred (see Section “Particular
Program Checks” in The Autoconf Manual).
AC_PROG_LEX
If a Lex source file is seen, then this macro must be used. See Section “Particular
Program Checks” in The Autoconf Manual.
AC_REQUIRE_AUX_FILE
For each AC_REQUIRE_AUX_FILE([file]), automake will ensure that file ex-
ists in the aux directory, and will complain otherwise. It will also automati-
cally distribute the file. This macro should be used by third-party Autoconf
macros that require some supporting files in the aux directory specified with
AC_CONFIG_AUX_DIR above. See Section “Finding configure Input” in The
Autoconf Manual.
AC_SUBST The first argument is automatically defined as a variable in each generated
Makefile.in. See Section “Setting Output Variables” in The Autoconf Man-
ual.
For every substituted variable var, automake will add a line var = value to
each Makefile.in file. Many Autoconf macros invoke AC_SUBST to set output
variables this way, e.g., AC_PATH_XTRA defines X_CFLAGS and X_LIBS. Thus, you
can access these variables as $(X_CFLAGS) and $(X_LIBS) in any Makefile.am
if AC_PATH_XTRA is called.
AM_C_PROTOTYPES
This is required when using the obsolete de-ANSI-fication feature; see
Section 8.17 [ANSI], page 76.
AM_CONDITIONAL
This introduces an Automake conditional (see Chapter 20 [Conditionals],
page 105).
AM_COND_IF
This macro allows automake to detect subsequent access within configure.ac
to a conditional previously introduced with AM_CONDITIONAL, thus enabling
conditional AC_CONFIG_FILES (see Chapter 20 [Conditionals], page 105).
AM_GNU_GETTEXT
This macro is required for packages that use GNU gettext (see Section 10.2
[gettext], page 85). It is distributed with gettext. If Automake sees this macro
it ensures that the package meets some of gettext’s requirements.
AM_GNU_GETTEXT_INTL_SUBDIR
This macro specifies that the intl/ subdirectory is to be built, even if the
AM_GNU_GETTEXT macro was invoked with a first argument of ‘external’.
Chapter 6: Scanning configure.ac 33
AM_MAINTAINER_MODE
This macro adds a --enable-maintainer-mode option to configure. If this
is used, automake will cause “maintainer-only” rules to be turned off by de-
fault in the generated Makefile.ins. This macro defines the MAINTAINER_MODE
conditional, which you can use in your own Makefile.am. See Section 27.2
[maintainer-mode], page 117.
m4_include
Files included by configure.ac using this macro will be detected by Au-
tomake and automatically distributed. They will also appear as dependencies
in Makefile rules.
m4_include is seldom used by configure.ac authors, but can appear in
aclocal.m4 when aclocal detects that some required macros come from
files local to your package (as opposed to macros installed in a system-wide
directory, see Section 6.3 [Invoking aclocal], page 33).
6.3 Auto-generating aclocal.m4
Automake includes a number of Autoconf macros that can be used in your package (see
Section 6.4 [Macros], page 42); some of them are actually required by Automake in certain
situations. These macros must be defined in your aclocal.m4; otherwise they will not be
seen by autoconf.
The aclocal program will automatically generate aclocal.m4 files based on the con-
tents of configure.ac. This provides a convenient way to get Automake-provided macros,
without having to search around. The aclocal mechanism allows other packages to supply
their own macros (see Section 6.3.3 [Extending aclocal], page 37). You can also use it to
maintain your own set of custom macros (see Section 6.3.4 [Local Macros], page 38).
At startup, aclocal scans all the .m4 files it can find, looking for macro definitions (see
Section 6.3.2 [Macro search path], page 35). Then it scans configure.ac. Any mention
of one of the macros found in the first step causes that macro, and any macros it in turn
requires, to be put into aclocal.m4.
Putting the file that contains the macro definition into aclocal.m4 is usually done by
copying the entire text of this file, including unused macro definitions as well as both ‘#’
and ‘dnl’ comments. If you want to make a comment that will be completely ignored by
aclocal, use ‘##’ as the comment leader.
When a file selected by aclocal is located in a subdirectory specified as a relative search
path with aclocal’s -I argument, aclocal assumes the file belongs to the package and uses
m4_include instead of copying it into aclocal.m4. This makes the package smaller, eases
dependency tracking, and cause the file to be distributed automatically. (See Section 6.3.4
[Local Macros], page 38, for an example.) Any macro that is found in a system-wide
directory, or via an absolute search path will be copied. So use ‘-I ‘pwd‘/reldir’ instead
of ‘-I reldir’ whenever some relative directory need to be considered outside the package.
The contents of acinclude.m4, if this file exists, are also automatically included in
aclocal.m4. We recommend against using acinclude.m4 in new packages (see Section 6.3.4
[Local Macros], page 38).
While computing aclocal.m4, aclocal runs autom4te (see Section “Using Autom4te”
in The Autoconf Manual) in order to trace the macros that are really used, and omit from
Chapter 6: Scanning configure.ac 34
aclocal.m4 all macros that are mentioned but otherwise unexpanded (this can happen
when a macro is called conditionally). autom4te is expected to be in the PATH, just as
autoconf. Its location can be overridden using the AUTOM4TE environment variable.
6.3.1 aclocal options
aclocal accepts the following options:
--acdir=dir
Look for the macro files in dir instead of the installation directory. This is
typically used for debugging.
--diff[=command]
Run command on M4 file that would be installed or overwritten by --install.
The default command is ‘diff -u’. This option implies --install and --dry-
run.
--dry-run
Do not actually overwrite (or create) aclocal.m4 and M4 files installed by
--install.
--help Print a summary of the command line options and exit.
-I dir Add the directory dir to the list of directories searched for .m4 files.
--install
Install system-wide third-party macros into the first directory specified with ‘-I
dir’ instead of copying them in the output file.
When this option is used, and only when this option is used, aclocal will also
honor ‘#serial NUMBER’ lines that appear in macros: an M4 file is ignored if
there exists another M4 file with the same basename and a greater serial number
in the search path (see Section 6.3.5 [Serials], page 39).
--force Always overwrite the output file. The default is to overwrite the output file only
when really needed, i.e., when its contents changes or if one of its dependencies
is younger.
This option forces the update of aclocal.m4 (or the file specified with --output
below) and only this file, it has absolutely no influence on files that may need
to be installed by --install.
--output=file
Cause the output to be put into file instead of aclocal.m4.
--print-ac-dir
Prints the name of the directory that aclocal will search to find third-party
.m4 files. When this option is given, normal processing is suppressed. This
option can be used by a package to determine where to install a macro file.
--verbose
Print the names of the files it examines.
--version
Print the version number of Automake and exit.
Chapter 6: Scanning configure.ac 35
-W CATEGORY
--warnings=category
Output warnings falling in category. category can be one of:
syntax dubious syntactic constructs, underquoted macros, unused macros,
etc.
unsupported
unknown macros
all all the warnings, this is the default
none turn off all the warnings
error treat warnings as errors
All warnings are output by default.
The environment variable WARNINGS is honored in the same way as it is for
automake (see Chapter 5 [Invoking Automake], page 25).
6.3.2 Macro search path
By default, aclocal searches for .m4 files in the following directories, in this order:
acdir-APIVERSION
This is where the .m4 macros distributed with automake itself are stored.
APIVERSION depends on the automake release used; for automake 1.6.x,
APIVERSION = 1.6.
acdir This directory is intended for third party .m4 files, and is configured when
automake itself is built. This is @datadir@/aclocal/, which typically expands
to ${prefix}/share/aclocal/. To find the compiled-in value of acdir, use the
--print-ac-dir option (see Section 6.3.1 [aclocal options], page 34).
As an example, suppose that automake-1.6.2 was configured with --prefix=
/usr/local. Then, the search path would be:
1. /usr/local/share/aclocal-1.6/
2. /usr/local/share/aclocal/
As explained in (see Section 6.3.1 [aclocal options], page 34), there are several options
that can be used to change or extend this search path.
6.3.2.1 Modifying the macro search path: --acdir
The most erroneous option to modify the search path is --acdir=dir, which changes
default directory and drops the APIVERSION directory. For example, if one specifies
‘--acdir=/opt/private/’, then the search path becomes:
1. /opt/private/
This option, --acdir, is intended for use by the internal automake test suite only; it is
not ordinarily needed by end-users.
Chapter 6: Scanning configure.ac 36
6.3.2.2 Modifying the macro search path: ‘-I dir’
Any extra directories specified using -I options (see Section 6.3.1 [aclocal options], page 34)
are prepended to this search list. Thus, ‘aclocal -I /foo -I /bar’ results in the following
search path:
1. /foo
2. /bar
3. acdir-APIVERSION
4. acdir
6.3.2.3 Modifying the macro search path: dirlist
There is a third mechanism for customizing the search path. If a dirlist file exists in
acdir, then that file is assumed to contain a list of directory patterns, one per line. aclocal
expands these patterns to directory names, and adds them to the search list after all other
directories. dirlist entries may use shell wildcards such as ‘*’, ‘?’, or [...].
For example, suppose acdir/dirlist contains the following:
/test1
/test2
/test3*
and that aclocal was called with the ‘-I /foo -I /bar’ options. Then, the search path
would be
1. /foo
2. /bar
3. acdir-APIVERSION
4. acdir
5. /test1
6. /test2
and all directories with path names starting with /test3.
If the --acdir=dir option is used, then aclocal will search for the dirlist file
in dir. In the ‘--acdir=/opt/private/’ example above, aclocal would look for
/opt/private/dirlist. Again, however, the --acdir option is intended for use by the
internal automake test suite only; --acdir is not ordinarily needed by end-users.
dirlist is useful in the following situation: suppose that automake version 1.6.2 is
installed with ‘--prefix=/usr’ by the system vendor. Thus, the default search directories
are
1. /usr/share/aclocal-1.6/
2. /usr/share/aclocal/
However, suppose further that many packages have been manually installed on the sys-
tem, with $prefix=/usr/local, as is typical. In that case, many of these “extra” .m4 files are
in /usr/local/share/aclocal. The only way to force /usr/bin/aclocal to find these
“extra” .m4 files is to always call ‘aclocal -I /usr/local/share/aclocal’. This is incon-
venient. With dirlist, one may create a file /usr/share/aclocal/dirlist containing
only the single line
/usr/local/share/aclocal
Chapter 6: Scanning configure.ac 37
Now, the “default” search path on the affected system is
1. /usr/share/aclocal-1.6/
2. /usr/share/aclocal/
3. /usr/local/share/aclocal/
without the need for -I options; -I options can be reserved for project-specific needs
(my-source-dir/m4/), rather than using it to work around local system-dependent tool
installation directories.
Similarly, dirlist can be handy if you have installed a local copy Automake on your
account and want aclocal to look for macros installed at other places on the system.
6.3.3 Writing your own aclocal macros
The aclocal program doesn’t have any built-in knowledge of any macros, so it is easy to
extend it with your own macros.
This can be used by libraries that want to supply their own Autoconf macros for use by
other programs. For instance, the gettext library supplies a macro AM_GNU_GETTEXT that
should be used by any package using gettext. When the library is installed, it installs this
macro so that aclocal will find it.
A macro file’s name should end in .m4. Such files should be installed in
$(datadir)/aclocal. This is as simple as writing:
aclocaldir = $(datadir)/aclocal
aclocal_DATA = mymacro.m4 myothermacro.m4
Please do use $(datadir)/aclocal, and not something based on the result of ‘aclocal
--print-ac-dir’. See Section 27.10 [Hard-Coded Install Paths], page 129, for arguments.
A file of macros should be a series of properly quoted AC_DEFUN’s (see Section “Macro Def-
initions” in The Autoconf Manual). The aclocal programs also understands AC_REQUIRE
(see Section “Prerequisite Macros” in The Autoconf Manual), so it is safe to put each macro
in a separate file. Each file should have no side effects but macro definitions. Especially,
any call to AC_PREREQ should be done inside the defined macro, not at the beginning of the
file.
Starting with Automake 1.8, aclocal will warn about all underquoted calls to AC_
DEFUN. We realize this will annoy a lot of people, because aclocal was not so strict in
the past and many third party macros are underquoted; and we have to apologize for this
temporary inconvenience. The reason we have to be stricter is that a future implementation
of aclocal (see Section 6.3.6 [Future of aclocal], page 41) will have to temporarily include
all these third party .m4 files, maybe several times, including even files that are not actually
needed. Doing so should alleviate many problems of the current implementation, however
it requires a stricter style from the macro authors. Hopefully it is easy to revise the existing
macros. For instance,
# bad style
AC_PREREQ(2.57)
AC_DEFUN(AX_FOOBAR,
[AC_REQUIRE([AX_SOMETHING])dnl
AX_FOO
AX_BAR
Chapter 6: Scanning configure.ac 38
])
should be rewritten as
AC_DEFUN([AX_FOOBAR],
[AC_PREREQ([2.57])dnl
AC_REQUIRE([AX_SOMETHING])dnl
AX_FOO
AX_BAR
])
Wrapping the AC_PREREQ call inside the macro ensures that Autoconf 2.57 will not be
required if AX_FOOBAR is not actually used. Most importantly, quoting the first argument of
AC_DEFUN allows the macro to be redefined or included twice (otherwise this first argument
would be expanded during the second definition). For consistency we like to quote even
arguments such as 2.57 that do not require it.
If you have been directed here by the aclocal diagnostic but are not the maintainer
of the implicated macro, you will want to contact the maintainer of that macro. Please
make sure you have the last version of the macro and that the problem already hasn’t been
reported before doing so: people tend to work faster when they aren’t flooded by mails.
Another situation where aclocal is commonly used is to manage macros that are used
locally by the package, Section 6.3.4 [Local Macros], page 38.
6.3.4 Handling Local Macros
Feature tests offered by Autoconf do not cover all needs. People often have to supplement
existing tests with their own macros, or with third-party macros.
There are two ways to organize custom macros in a package.
The first possibility (the historical practice) is to list all your macros in acinclude.m4.
This file will be included in aclocal.m4 when you run aclocal, and its macro(s) will
henceforth be visible to autoconf. However if it contains numerous macros, it will rapidly
become difficult to maintain, and it will be almost impossible to share macros between
packages.
The second possibility, which we do recommend, is to write each macro in its own file
and gather all these files in a directory. This directory is usually called m4/. To build
aclocal.m4, one should therefore instruct aclocal to scan m4/. From the command line,
this is done with ‘aclocal -I m4’. The top-level Makefile.am should also be updated to
define
ACLOCAL_AMFLAGS = -I m4
ACLOCAL_AMFLAGS contains options to pass to aclocal when aclocal.m4 is to be rebuilt
by make. This line is also used by autoreconf (see Section “Using autoreconf to Update
configure Scripts” in The Autoconf Manual) to run aclocal with suitable options, or
by autopoint (see Section “Invoking the autopoint Program” in GNU gettext tools) and
gettextize (see Section “Invoking the gettextize Program” in GNU gettext tools) to
locate the place where Gettext’s macros should be installed. So even if you do not really
care about the rebuild rules, you should define ACLOCAL_AMFLAGS.
When ‘aclocal -I m4’ is run, it will build a aclocal.m4 that m4_includes any file
from m4/ that defines a required macro. Macros not found locally will still be searched in
system-wide directories, as explained in Section 6.3.2 [Macro search path], page 35.
Chapter 6: Scanning configure.ac 39
Custom macros should be distributed for the same reason that configure.ac is: so that
other people have all the sources of your package if they want to work on it. Actually, this
distribution happens automatically because all m4_included files are distributed.
However there is no consensus on the distribution of third-party macros that your package
may use. Many libraries install their own macro in the system-wide aclocal directory (see
Section 6.3.3 [Extending aclocal], page 37). For instance, Guile ships with a file called
guile.m4 that contains the macro GUILE_FLAGS that can be used to define setup compiler
and linker flags appropriate for using Guile. Using GUILE_FLAGS in configure.ac will cause
aclocal to copy guile.m4 into aclocal.m4, but as guile.m4 is not part of the project, it
will not be distributed. Technically, that means a user who needs to rebuild aclocal.m4 will
have to install Guile first. This is probably OK, if Guile already is a requirement to build
the package. However, if Guile is only an optional feature, or if your package might run
on architectures where Guile cannot be installed, this requirement will hinder development.
An easy solution is to copy such third-party macros in your local m4/ directory so they get
distributed.
Since Automake 1.10, aclocal offers an option to copy these system-wide third-party
macros in your local macro directory, solving the above problem. Simply use:
ACLOCAL_AMFLAGS = -I m4 --install
With this setup, system-wide macros will be copied to m4/ the first time you run
autoreconf. Then the locally installed macros will have precedence over the system-wide
installed macros each time aclocal is run again.
One reason why you should keep --install in the flags even after the first run is that
when you later edit configure.ac and depend on a new macro, this macro will be installed
in your m4/ automatically. Another one is that serial numbers (see Section 6.3.5 [Serials],
page 39) can be used to update the macros in your source tree automatically when new
system-wide versions are installed. A serial number should be a single line of the form
#serial NNN
where NNN contains only digits and dots. It should appear in the M4 file before any macro
definition. It is a good practice to maintain a serial number for each macro you distribute,
even if you do not use the --install option of aclocal: this allows other people to use it.
6.3.5 Serial Numbers
Because third-party macros defined in *.m4 files are naturally shared between multiple
projects, some people like to version them. This makes it easier to tell which of two M4
files is newer. Since at least 1996, the tradition is to use a ‘#serial’ line for this.
A serial number should be a single line of the form
# serial version
where version is a version number containing only digits and dots. Usually people use a
single integer, and they increment it each time they change the macro (hence the name of
“serial”). Such a line should appear in the M4 file before any macro definition.
The ‘#’ must be the first character on the line, and it is OK to have extra words after
the version, as in
#serial version garbage
Chapter 6: Scanning configure.ac 40
Normally these serial numbers are completely ignored by aclocal and autoconf, like any
genuine comment. However when using aclocal’s --install feature, these serial numbers
will modify the way aclocal selects the macros to install in the package: if two files with
the same basename exists in your search path, and if at least one of them use a ‘#serial’
line, aclocal will ignore the file that has the older ‘#serial’ line (or the file that has none).
Note that a serial number applies to a whole M4 file, not to any macro it contains. A
file can contains multiple macros, but only one serial.
Here is a use case that illustrate the use of --install and its interaction
with serial numbers. Let’s assume we maintain a package called MyPackage, the
configure.ac of which requires a third-party macro AX_THIRD_PARTY defined in
/usr/share/aclocal/thirdparty.m4 as follows:
# serial 1
AC_DEFUN([AX_THIRD_PARTY], [...])
MyPackage uses an m4/ directory to store local macros as explained in Section 6.3.4
[Local Macros], page 38, and has
ACLOCAL_AMFLAGS = -I m4 --install
in its top-level Makefile.am.
Initially the m4/ directory is empty. The first time we run autoreconf, it will fetch the
options to pass to aclocal in Makefile.am, and run ‘aclocal -I m4 --install’. aclocal
will notice that
• configure.ac uses AX_THIRD_PARTY
• No local macros define AX_THIRD_PARTY
• /usr/share/aclocal/thirdparty.m4 defines AX_THIRD_PARTY with serial 1.
Because /usr/share/aclocal/thirdparty.m4 is a system-wide macro and aclocal was
given the --install option, it will copy this file in m4/thirdparty.m4, and output an
aclocal.m4 that contains ‘m4_include([m4/thirdparty.m4])’.
The next time ‘aclocal -I m4 --install’ is run (either via autoreconf, by hand, or
from the Makefile rebuild rules) something different happens. aclocal notices that
• configure.ac uses AX_THIRD_PARTY
• m4/thirdparty.m4 defines AX_THIRD_PARTY with serial 1.
• /usr/share/aclocal/thirdparty.m4 defines AX_THIRD_PARTY with serial 1.
Because both files have the same serial number, aclocal uses the first it found in its
search path order (see Section 6.3.2 [Macro search path], page 35). aclocal therefore
ignores /usr/share/aclocal/thirdparty.m4 and outputs an aclocal.m4 that contains
‘m4_include([m4/thirdparty.m4])’.
Local directories specified with -I are always searched before system-wide directories, so
a local file will always be preferred to the system-wide file in case of equal serial numbers.
Now suppose the system-wide third-party macro is changed. This can happen if the
package installing this macro is updated. Let’s suppose the new macro has serial number
2. The next time ‘aclocal -I m4 --install’ is run the situation is the following:
• configure.ac uses AX_THIRD_PARTY
• m4/thirdparty.m4 defines AX_THIRD_PARTY with serial 1.
Chapter 6: Scanning configure.ac 41
• /usr/share/aclocal/thirdparty.m4 defines AX_THIRD_PARTY with serial 2.
When aclocal sees a greater serial number, it immediately forgets anything it knows from
files that have the same basename and a smaller serial number. So after it has found
/usr/share/aclocal/thirdparty.m4 with serial 2, aclocal will proceed as if it had never
seen m4/thirdparty.m4. This brings us back to a situation similar to that at the beginning
of our example, where no local file defined the macro. aclocal will install the new version
of the macro in m4/thirdparty.m4, in this case overriding the old version. MyPackage just
had its macro updated as a side effect of running aclocal.
If you are leery of letting aclocal update your local macro, you can run ‘aclocal -I m4
--diff’ to review the changes ‘aclocal -I m4 --install’ would perform on these macros.
Finally, note that the --force option of aclocal has absolutely no effect on the files
installed by --install. For instance, if you have modified your local macros, do not
expect --install --force to replace the local macros by their system-wide versions. If
you want to do so, simply erase the local macros you want to revert, and run ‘aclocal -I
m4 --install’.
6.3.6 The Future of aclocal
aclocal is expected to disappear. This feature really should not be offered by Automake.
Automake should focus on generating Makefiles; dealing with M4 macros really is Au-
toconf’s job. That some people install Automake just to use aclocal, but do not use
automake otherwise is an indication of how that feature is misplaced.
The new implementation will probably be done slightly differently. For instance, it could
enforce the m4/-style layout discussed in Section 6.3.4 [Local Macros], page 38.
We have no idea when and how this will happen. This has been discussed several times
in the past, but someone still has to commit itself to that non-trivial task.
From the user point of view, aclocal’s removal might turn out to be painful. There is a
simple precaution that you may take to make that switch more seamless: never call aclocal
yourself. Keep this guy under the exclusive control of autoreconf and Automake’s rebuild
rules. Hopefully you won’t need to worry about things breaking, when aclocal disappears,
because everything will have been taken care of. If otherwise you used to call aclocal
directly yourself or from some script, you will quickly notice the change.
Many packages come with a script called bootstrap.sh or autogen.sh, that will just call
aclocal, libtoolize, gettextize or autopoint, autoconf, autoheader, and automake
in the right order. Actually this is precisely what autoreconf can do for you. If your
package has such a bootstrap.sh or autogen.sh script, consider using autoreconf. That
should simplify its logic a lot (less things to maintain, yum!), it’s even likely you will not
need the script anymore, and more to the point you will not call aclocal directly anymore.
For the time being, third-party packages should continue to install public macros into
/usr/share/aclocal/. If aclocal is replaced by another tool it might make sense to
rename the directory, but supporting /usr/share/aclocal/ for backward compatibility
should be really easy provided all macros are properly written (see Section 6.3.3 [Extending
aclocal], page 37).
Chapter 6: Scanning configure.ac 42
6.4 Autoconf macros supplied with Automake
Automake ships with several Autoconf macros that you can use from your configure.ac.
When you use one of them it will be included by aclocal in aclocal.m4.
6.4.1 Public macros
AM_ENABLE_MULTILIB
This is used when a “multilib” library is being built. The first optional argument
is the name of the Makefile being generated; it defaults to ‘Makefile’. The
second option argument is used to find the top source directory; it defaults to
the empty string (generally this should not be used unless you are familiar with
the internals). See Section 18.3 [Multilibs], page 104.
AM_INIT_AUTOMAKE([OPTIONS])
AM_INIT_AUTOMAKE(PACKAGE, VERSION, [NO-DEFINE])
Runs many macros required for proper operation of the generated Makefiles.
This macro has two forms, the first of which is preferred. In this form, AM_INIT_
AUTOMAKE is called with a single argument: a space-separated list of Automake
options that should be applied to every Makefile.am in the tree. The effect is
as if each option were listed in AUTOMAKE_OPTIONS (see Chapter 17 [Options],
page 99).
The second, deprecated, form of AM_INIT_AUTOMAKE has two required argu-
ments: the package and the version number. This form is obsolete because the
package and version can be obtained from Autoconf’s AC_INIT macro (which
itself has an old and a new form).
If your configure.ac has:
AC_INIT([src/foo.c])
AM_INIT_AUTOMAKE([mumble], [1.5])
you can modernize it as follows:
AC_INIT([mumble], [1.5])
AC_CONFIG_SRCDIR([src/foo.c])
AM_INIT_AUTOMAKE
Note that if you’re upgrading your configure.ac from an earlier version of
Automake, it is not always correct to simply move the package and version
arguments from AM_INIT_AUTOMAKE directly to AC_INIT, as in the example
above. The first argument to AC_INIT should be the name of your package
(e.g., ‘GNU Automake’), not the tarball name (e.g., ‘automake’) that you used
to pass to AM_INIT_AUTOMAKE. Autoconf tries to derive a tarball name from
the package name, which should work for most but not all package names. (If
it doesn’t work for yours, you can use the four-argument form of AC_INIT to
provide the tarball name explicitly).
By default this macro AC_DEFINE’s PACKAGE and VERSION. This can be avoided
by passing the no-define option, as in:
AM_INIT_AUTOMAKE([gnits 1.5 no-define dist-bzip2])
or by passing a third non-empty argument to the obsolete form.
Chapter 6: Scanning configure.ac 43
AM_PATH_LISPDIR
Searches for the program emacs, and, if found, sets the output variable lispdir
to the full path to Emacs’ site-lisp directory.
Note that this test assumes the emacs found to be a version that supports
Emacs Lisp (such as gnu Emacs or XEmacs). Other emacsen can cause this
test to hang (some, like old versions of MicroEmacs, start up in interactive
mode, requiring C-x C-c to exit, which is hardly obvious for a non-emacs user).
In most cases, however, you should be able to use C-c to kill the test. In
order to avoid problems, you can set EMACS to “no” in the environment, or use
the --with-lispdir option to configure to explicitly set the correct path (if
you’re sure you have an emacs that supports Emacs Lisp).
AM_PROG_AS
Use this macro when you have assembly code in your project. This will choose
the assembler for you (by default the C compiler) and set CCAS, and will also
set CCASFLAGS if required.
AM_PROG_CC_C_O
This is like AC_PROG_CC_C_O, but it generates its results in the manner required
by automake. You must use this instead of AC_PROG_CC_C_O when you need
this functionality, that is, when using per-target flags or subdir-objects with C
sources.
AM_PROG_LEX
Like AC_PROG_LEX (see Section “Particular Program Checks” in The Autoconf
Manual), but uses the missing script on systems that do not have lex. HP-UX
10 is one such system.
AM_PROG_GCJ
This macro finds the gcj program or causes an error. It sets GCJ and GCJFLAGS.
gcj is the Java front-end to the GNU Compiler Collection.
AM_PROG_UPC([compiler-search-list])
Find a compiler for Unified Parallel C and define the UPC variable. The de-
fault compiler-search-list is ‘upcc upc’. This macro will abort configure if no
Unified Parallel C compiler is found.
AM_WITH_DMALLOC
Add support for the Dmalloc package (http://dmalloc.com/). If the user
runs configure with --with-dmalloc, then define WITH_DMALLOC and add
-ldmalloc to LIBS.
AM_WITH_REGEX
Adds --with-regex to the configure command line. If specified (the default),
then the ‘regex’ regular expression library is used, regex.o is put into LIBOBJS,
and WITH_REGEX is defined. If --without-regex is given, then the rx regular
expression library is used, and rx.o is put into LIBOBJS.
6.4.2 Obsolete macros
Although using some of the following macros was required in past releases, you should not
use any of them in new code. Running autoupdate should adjust your configure.ac au-
Chapter 6: Scanning configure.ac 44
tomatically (see Section “Using autoupdate to Modernize configure.ac” in The Autoconf
Manual).
AM_C_PROTOTYPES
Check to see if function prototypes are understood by the compiler. If so, define
‘PROTOTYPES’ and set the output variables U and ANSI2KNR to the empty string.
Otherwise, set U to ‘_’ and ANSI2KNR to ‘./ansi2knr’. Automake uses these
values to implement the obsolete de-ANSI-fication feature.
AM_CONFIG_HEADER
Automake will generate rules to automatically regenerate the config header.
This obsolete macro is a synonym of AC_CONFIG_HEADERS today (see Section 6.2
[Optional], page 30).
AM_HEADER_TIOCGWINSZ_NEEDS_SYS_IOCTL
If the use of TIOCGWINSZ requires <sys/ioctl.h>, then define GWINSZ_IN_SYS_
IOCTL. Otherwise TIOCGWINSZ can be found in <termios.h>. This macro is
obsolete, you should use Autoconf’s AC_HEADER_TIOCGWINSZ instead.
AM_PROG_MKDIR_P
From Automake 1.8 to 1.9.6 this macro used to define the output variable
mkdir_p to one of mkdir -p, install-sh -d, or mkinstalldirs.
Nowadays Autoconf provides a similar functionality with AC_PROG_MKDIR_P (see
Section “Particular Program Checks” in The Autoconf Manual), however this
defines the output variable MKDIR_P instead. Therefore AM_PROG_MKDIR_P has
been rewritten as a thin wrapper around AC_PROG_MKDIR_P to define mkdir_p
to the same value as MKDIR_P for backward compatibility.
If you are using Automake, there is normally no reason to call this macro, be-
cause AM_INIT_AUTOMAKE already does so. However, make sure that the custom
rules in your Makefiles use $(MKDIR_P) and not $(mkdir_p). Even if both
variables still work, the latter should be considered obsolete.
If you are not using Automake, please call AC_PROG_MKDIR_P instead of AM_
PROG_MKDIR_P.
AM_SYS_POSIX_TERMIOS
Check to see if POSIX termios headers and functions are available on the sys-
tem. If so, set the shell variable am_cv_sys_posix_termios to ‘yes’. If not,
set the variable to ‘no’. This macro is obsolete, you should use Autoconf’s
AC_SYS_POSIX_TERMIOS instead.
6.4.3 Private macros
The following macros are private macros you should not call directly. They are called by
the other public macros when appropriate. Do not rely on them, as they might be changed
in a future version. Consider them as implementation details; or better, do not consider
them at all: skip this section!
Chapter 7: Directories 45
_AM_DEPENDENCIES
AM_SET_DEPDIR
AM_DEP_TRACK
AM_OUTPUT_DEPENDENCY_COMMANDS
These macros are used to implement Automake’s automatic dependency track-
ing scheme. They are called automatically by automake when required, and
there should be no need to invoke them manually.
AM_MAKE_INCLUDE
This macro is used to discover how the user’s make handles include statements.
This macro is automatically invoked when needed; there should be no need to
invoke it manually.
AM_PROG_INSTALL_STRIP
This is used to find a version of install that can be used to strip a program
at installation time. This macro is automatically included when required.
AM_SANITY_CHECK
This checks to make sure that a file created in the build directory is newer than
a file in the source directory. This can fail on systems where the clock is set
incorrectly. This macro is automatically run from AM_INIT_AUTOMAKE.
7 Directories
For simple projects that distributes all files in the same directory it is enough to have a
single Makefile.am that builds everything in place.
In larger projects it is common to organize files in different directories, in a tree. For in-
stance one directory per program, per library or per module. The traditional approach is to
build these subdirectory recursively: each directory contains its Makefile (generated from
Makefile.am), and when make is run from the top level directory it enters each subdirectory
in turn to build its contents.
7.1 Recursing subdirectories
In packages with subdirectories, the top level Makefile.am must tell Automake which
subdirectories are to be built. This is done via the SUBDIRS variable.
The SUBDIRS variable holds a list of subdirectories in which building of various sorts can
occur. The rules for many targets (e.g., all) in the generated Makefile will run commands
both locally and in all specified subdirectories. Note that the directories listed in SUBDIRS
are not required to contain Makefile.ams; only Makefiles (after configuration). This allows
inclusion of libraries from packages that do not use Automake (such as gettext; see also
Section 23.2 [Third-Party Makefiles], page 110).
In packages that use subdirectories, the top-level Makefile.am is often very short. For
instance, here is the Makefile.am from the GNU Hello distribution:
EXTRA_DIST = BUGS ChangeLog.O README-alpha
SUBDIRS = doc intl po src tests
Chapter 7: Directories 46
When Automake invokes make in a subdirectory, it uses the value of the MAKE variable.
It passes the value of the variable AM_MAKEFLAGS to the make invocation; this can be set in
Makefile.am if there are flags you must always pass to make.
The directories mentioned in SUBDIRS are usually direct children of the current direc-
tory, each subdirectory containing its own Makefile.am with a SUBDIRS pointing to deeper
subdirectories. Automake can be used to construct packages of arbitrary depth this way.
By default, Automake generates Makefiles that work depth-first in postfix order: the
subdirectories are built before the current directory. However, it is possible to change this
ordering. You can do this by putting ‘.’ into SUBDIRS. For instance, putting ‘.’ first will
cause a prefix ordering of directories.
Using
SUBDIRS = lib src . test
will cause lib/ to be built before src/, then the current directory will be built, finally the
test/ directory will be built. It is customary to arrange test directories to be built after
everything else since they are meant to test what has been constructed.
All clean rules are run in reverse order of build rules.
7.2 Conditional Subdirectories
It is possible to define the SUBDIRS variable conditionally if, like in the case of GNU Inetutils,
you want to only build a subset of the entire package.
To illustrate how this works, let’s assume we have two directories src/ and opt/. src/
should always be built, but we want to decide in configure whether opt/ will be built
or not. (For this example we will assume that opt/ should be built when the variable
‘$want_opt’ was set to ‘yes’.)
Running make should thus recurse into src/ always, and then maybe in opt/.
However ‘make dist’ should always recurse into both src/ and opt/. Because opt/
should be distributed even if it is not needed in the current configuration. This means
opt/Makefile should be created unconditionally.
There are two ways to setup a project like this. You can use Automake conditionals
(see Chapter 20 [Conditionals], page 105) or use Autoconf AC_SUBST variables (see Section
“Setting Output Variables” in The Autoconf Manual). Using Automake conditionals is the
preferred solution. Before we illustrate these two possibilities, let’s introduce DIST_SUBDIRS.
7.2.1 SUBDIRS vs. DIST_SUBDIRS
Automake considers two sets of directories, defined by the variables SUBDIRS and DIST_
SUBDIRS.
SUBDIRS contains the subdirectories of the current directory that must be built (see
Section 7.1 [Subdirectories], page 45). It must be defined manually; Automake will never
guess a directory is to be built. As we will see in the next two sections, it is possible to
define it conditionally so that some directory will be omitted from the build.
DIST_SUBDIRS is used in rules that need to recurse in all directories, even those that
have been conditionally left out of the build. Recall our example where we may not want
to build subdirectory opt/, but yet we want to distribute it? This is where DIST_SUBDIRS
come into play: ‘opt’ may not appear in SUBDIRS, but it must appear in DIST_SUBDIRS.
Chapter 7: Directories 47
Precisely, DIST_SUBDIRS is used by ‘make maintainer-clean’, ‘make distclean’ and
‘make dist’. All other recursive rules use SUBDIRS.
If SUBDIRS is defined conditionally using Automake conditionals, Automake will define
DIST_SUBDIRS automatically from the possibles values of SUBDIRS in all conditions.
If SUBDIRS contains AC_SUBST variables, DIST_SUBDIRS will not be defined correctly
because Automake does not know the possible values of these variables. In this case DIST_
SUBDIRS needs to be defined manually.
7.2.2 Conditional subdirectories with AM_CONDITIONAL
configure should output the Makefile for each directory and define a condition into which
opt/ should be built.
...
AM_CONDITIONAL([COND_OPT], [test "$want_opt" = yes])
AC_CONFIG_FILES([Makefile src/Makefile opt/Makefile])
...
Then SUBDIRS can be defined in the top-level Makefile.am as follows.
if COND_OPT
MAYBE_OPT = opt
endif
SUBDIRS = src $(MAYBE_OPT)
As you can see, running make will rightly recurse into src/ and maybe opt/.
As you can’t see, running ‘make dist’ will recurse into both src/ and opt/ directories
because ‘make dist’, unlike ‘make all’, doesn’t use the SUBDIRS variable. It uses the DIST_
SUBDIRS variable.
In this case Automake will define ‘DIST_SUBDIRS = src opt’ automatically because it
knows that MAYBE_OPT can contain ‘opt’ in some condition.
7.2.3 Conditional Subdirectories with AC_SUBST
Another possibility is to define MAYBE_OPT from ./configure using AC_SUBST:
...
if test "$want_opt" = yes; then
MAYBE_OPT=opt
else
MAYBE_OPT=
fi
AC_SUBST([MAYBE_OPT])
AC_CONFIG_FILES([Makefile src/Makefile opt/Makefile])
...
In this case the top-level Makefile.am should look as follows.
SUBDIRS = src $(MAYBE_OPT)
DIST_SUBDIRS = src opt
The drawback is that since Automake cannot guess what the possible values of MAYBE_
OPT are, it is necessary to define DIST_SUBDIRS.
Chapter 7: Directories 48
7.2.4 Non-configured Subdirectories
The semantic of DIST_SUBDIRS is often misunderstood by some users that try to configure
and build subdirectories conditionally. Here by configuring we mean creating the Makefile
(it might also involve running a nested configure script: this is a costly operation that
explains why people want to do it conditionally, but only the Makefile is relevant to the
discussion).
The above examples all assume that every Makefile is created, even in directories that
are not going to be built. The simple reason is that we want ‘make dist’ to distribute even
the directories that are not being built (e.g., platform-dependent code), hence make dist
must recurse into the subdirectory, hence this directory must be configured and appear in
DIST_SUBDIRS.
Building packages that do not configure every subdirectory is a tricky business, and we
do not recommend it to the novice as it is easy to produce an incomplete tarball by mistake.
We will not discuss this topic in depth here, yet for the adventurous here are a few rules to
remember.
• SUBDIRS should always be a subset of DIST_SUBDIRS.
It makes little sense to have a directory in SUBDIRS that is not in DIST_SUBDIRS. Think
of the former as a way to tell which directories listed in the latter should be built.
• Any directory listed in DIST_SUBDIRS and SUBDIRS must be configured.
I.e., the Makefile must exists or the recursive make rules will not be able to process
the directory.
• Any configured directory must be listed in DIST_SUBDIRS.
So that the cleaning rule remove the generated Makefiles. It would be correct to see
DIST_SUBDIRS as a variable that lists all the directories that have been configured.
In order to prevent recursion in some non-configured directory you must therefore ensure
that this directory does not appear in DIST_SUBDIRS (and SUBDIRS). For instance, if you
define SUBDIRS conditionally using AC_SUBST and do not define DIST_SUBDIRS explicitly, it
will be default to ‘$(SUBDIRS)’; another possibility is to force DIST_SUBDIRS = $(SUBDIRS).
Of course, directories that are omitted from DIST_SUBDIRS will not be distributed unless
you make other arrangements for this to happen (for instance, always running ‘make dist’
in a configuration where all directories are known to appear in DIST_SUBDIRS; or writing a
dist-hook target to distribute these directories).
In few packages, non-configured directories are not even expected to be distributed.
Although these packages do not require the aforementioned extra arrangements, there is
another pitfall. If the name of a directory appears in SUBDIRS or DIST_SUBDIRS, automake
will make sure the directory exists. Consequently automake cannot be run on such a
distribution when one directory has been omitted. One way to avoid this check is to use
the AC_SUBST method to declare conditional directories; since automake does not know the
values of AC_SUBST variables it cannot ensure the corresponding directory exist.
Chapter 7: Directories 49
7.3 An Alternative Approach to Subdirectories
If you’ve ever read Peter Miller’s excellent paper, Recursive Make Considered Harmful
(http://www.pcug.org.au/~millerp/rmch/recu-make-cons-harm.html), the preceding
sections on the use of subdirectories will probably come as unwelcome advice. For those
who haven’t read the paper, Miller’s main thesis is that recursive make invocations are both
slow and error-prone.
Automake provides sufficient cross-directory support3 to enable you to write a single
Makefile.am for a complex multi-directory package.
By default an installable file specified in a subdirectory will have its directory name
stripped before installation. For instance, in this example, the header file will be installed
as $(includedir)/stdio.h:
include_HEADERS = inc/stdio.h
However, the ‘nobase_’ prefix can be used to circumvent this path stripping. In this
example, the header file will be installed as $(includedir)/sys/types.h:
nobase_include_HEADERS = sys/types.h
‘nobase_’ should be specified first when used in conjunction with either ‘dist_’ or
‘nodist_’ (see Chapter 14 [Dist], page 93). For instance:
nobase_dist_pkgdata_DATA = images/vortex.pgm sounds/whirl.ogg
Finally, note that a variable using the ‘nobase_’ prefix can always be replaced by several
variables, one for each destination directory (see Section 3.3 [Uniform], page 19). For
instance, the last example could be rewritten as follows:
imagesdir = $(pkgdatadir)/images
soundsdir = $(pkgdatadir)/sounds
dist_images_DATA = images/vortex.pgm
dist_sounds_DATA = sounds/whirl.ogg
This latter syntax makes it possible to change one destination directory without changing
the layout of the source tree.
7.4 Nesting Packages
In the GNU Build System, packages can be nested to arbitrary depth. This means that a
package can embedded other packages with their own configure, Makefiles, etc.
These other packages should just appear as subdirectories of their parent package.
They must be listed in SUBDIRS like other ordinary directories. However the subpackage’s
Makefiles should be output by its own configure script, not by the parent’s configure.
This is achieved using the AC_CONFIG_SUBDIRS Autoconf macro (see Section “Configuring
Other Packages in Subdirectories” in The Autoconf Manual).
Here is an example package for an arm program that links with an hand library that is
a nested package in subdirectory hand/.
arm’s configure.ac:
AC_INIT([arm], [1.0])
3
We believe. This work is new and there are probably warts. See Chapter 1 [Introduction], page 1, for
information on reporting bugs.
Chapter 7: Directories 50
AC_CONFIG_AUX_DIR([.])
AM_INIT_AUTOMAKE
AC_PROG_CC
AC_CONFIG_FILES([Makefile])
# Call hand’s ./configure script recursively.
AC_CONFIG_SUBDIRS([hand])
AC_OUTPUT
arm’s Makefile.am:
# Build the library in the hand subdirectory first.
SUBDIRS = hand
# Include hand’s header when compiling this directory.
AM_CPPFLAGS = -I$(srcdir)/hand
bin_PROGRAMS = arm
arm_SOURCES = arm.c
# link with the hand library.
arm_LDADD = hand/libhand.a
Now here is hand’s hand/configure.ac:
AC_INIT([hand], [1.2])
AC_CONFIG_AUX_DIR([.])
AM_INIT_AUTOMAKE
AC_PROG_CC
AC_PROG_RANLIB
AC_CONFIG_FILES([Makefile])
AC_OUTPUT
and its hand/Makefile.am:
lib_LIBRARIES = libhand.a
libhand_a_SOURCES = hand.c
When ‘make dist’ is run from the top-level directory it will create an archive
arm-1.0.tar.gz that contains the arm code as well as the hand subdirectory. This
package can be built and installed like any ordinary package, with the usual ‘./configure
&& make && make install’ sequence (the hand subpackage will be built and installed by
the process).
When ‘make dist’ is run from the hand directory, it will create a self-contained
hand-1.2.tar.gz archive. So although it appears to be embedded in another package, it
can still be used separately.
The purpose of the ‘AC_CONFIG_AUX_DIR([.])’ instruction is to force Automake and
Autoconf to search for auxiliary scripts in the current directory. For instance, this means
that there will be two copies of install-sh: one in the top-level of the arm package, and
another one in the hand/ subdirectory for the hand package.
The historical default is to search for these auxiliary scripts in the parent directory and
the grandparent directory. So if the ‘AC_CONFIG_AUX_DIR([.])’ line was removed from
hand/configure.ac, that subpackage would share the auxiliary script of the arm package.
This may looks like a gain in size (a few kilobytes), but it is actually a loss of modularity
Chapter 8: Building Programs and Libraries 51
as the hand subpackage is no longer self-contained (‘make dist’ in the subdirectory will not
work anymore).
Packages that do not use Automake need more work to be integrated this way. See
Section 23.2 [Third-Party Makefiles], page 110.
8 Building Programs and Libraries
A large part of Automake’s functionality is dedicated to making it easy to build programs
and libraries.
8.1 Building a program
In order to build a program, you need to tell Automake which sources are part of it, and
which libraries it should be linked with.
This section also covers conditional compilation of sources or programs. Most of the
comments about these also apply to libraries (see Section 8.2 [A Library], page 55) and
libtool libraries (see Section 8.3 [A Shared Library], page 55).
8.1.1 Defining program sources
In a directory containing source that gets built into a program (as opposed to a library or
a script), the PROGRAMS primary is used. Programs can be installed in bindir, sbindir,
libexecdir, pkglibdir, pkglibexecdir, or not at all (noinst_). They can also be built
only for ‘make check’, in which case the prefix is ‘check_’.
For instance:
bin_PROGRAMS = hello
In this simple case, the resulting Makefile.in will contain code to generate a program
named hello.
Associated with each program are several assisting variables that are named after the
program. These variables are all optional, and have reasonable defaults. Each variable, its
use, and default is spelled out below; we use the “hello” example throughout.
The variable hello_SOURCES is used to specify which source files get built into an exe-
cutable:
hello_SOURCES = hello.c version.c getopt.c getopt1.c getopt.h system.h
This causes each mentioned .c file to be compiled into the corresponding .o. Then all
are linked to produce hello.
If hello_SOURCES is not specified, then it defaults to the single file hello.c (see
Section 8.5 [Default SOURCES], page 65).
Multiple programs can be built in a single directory. Multiple programs can share a
single source file, which must be listed in each _SOURCES definition.
Header files listed in a _SOURCES definition will be included in the distribution but
otherwise ignored. In case it isn’t obvious, you should not include the header file generated
by configure in a _SOURCES variable; this file should not be distributed. Lex (.l) and
Yacc (.y) files can also be listed; see Section 8.8 [Yacc and Lex], page 69.
Chapter 8: Building Programs and Libraries 52
8.1.2 Linking the program
If you need to link against libraries that are not found by configure, you can use LDADD
to do so. This variable is used to specify additional objects or libraries to link with; it is
inappropriate for specifying specific linker flags, you should use AM_LDFLAGS for this purpose.
Sometimes, multiple programs are built in one directory but do not share the same
link-time requirements. In this case, you can use the prog_LDADD variable (where prog is
the name of the program as it appears in some _PROGRAMS variable, and usually written in
lowercase) to override the global LDADD. If this variable exists for a given program, then
that program is not linked using LDADD.
For instance, in GNU cpio, pax, cpio and mt are linked against the library libcpio.a.
However, rmt is built in the same directory, and has no such link requirement. Also, mt and
rmt are only built on certain architectures. Here is what cpio’s src/Makefile.am looks like
(abridged):
bin_PROGRAMS = cpio pax $(MT)
libexec_PROGRAMS = $(RMT)
EXTRA_PROGRAMS = mt rmt
LDADD = ../lib/libcpio.a $(INTLLIBS)
rmt_LDADD =
cpio_SOURCES = ...
pax_SOURCES = ...
mt_SOURCES = ...
rmt_SOURCES = ...
prog_LDADD is inappropriate for passing program-specific linker flags (except for -l, -L,
-dlopen and -dlpreopen). So, use the prog_LDFLAGS variable for this purpose.
It is also occasionally useful to have a program depend on some other target that is not
actually part of that program. This can be done using the prog_DEPENDENCIES variable.
Each program depends on the contents of such a variable, but no further interpretation is
done.
Since these dependencies are associated to the link rule used to create the programs they
should normally list files used by the link command. That is *.$(OBJEXT), *.a, or *.la
files. In rare cases you may need to add other kinds of files such as linker scripts, but listing
a source file in _DEPENDENCIES is wrong. If some source file needs to be built before all the
components of a program are built, consider using the BUILT_SOURCES variable instead (see
Section 9.4 [Sources], page 80).
If prog_DEPENDENCIES is not supplied, it is computed by Automake. The automatically-
assigned value is the contents of prog_LDADD, with most configure substitutions, -l, -L,
-dlopen and -dlpreopen options removed. The configure substitutions that are left in are
only ‘$(LIBOBJS)’ and ‘$(ALLOCA)’; these are left because it is known that they will not
cause an invalid value for prog_DEPENDENCIES to be generated.
Section 8.1.3 [Conditional Sources], page 53, shows a situation where _DEPENDENCIES
may be used.
Chapter 8: Building Programs and Libraries 53
We recommend that you avoid using -l options in LDADD or prog_LDADD when referring
to libraries built by your package. Instead, write the file name of the library explicitly as
in the above cpio example. Use -l only to list third-party libraries. If you follow this rule,
the default value of prog_DEPENDENCIES will list all your local libraries and omit the other
ones.
8.1.3 Conditional compilation of sources
You can’t put a configure substitution (e.g., ‘@FOO@’ or ‘$(FOO)’ where FOO is defined via
AC_SUBST) into a _SOURCES variable. The reason for this is a bit hard to explain, but suffice
to say that it simply won’t work. Automake will give an error if you try to do this.
Fortunately there are two other ways to achieve the same result. One is to use configure
substitutions in _LDADD variables, the other is to use an Automake conditional.
8.1.3.1 Conditional compilation using _LDADD substitutions
Automake must know all the source files that could possibly go into a program, even if
not all the files are built in every circumstance. Any files that are only conditionally built
should be listed in the appropriate EXTRA_ variable. For instance, if hello-linux.c or
hello-generic.c were conditionally included in hello, the Makefile.am would contain:
bin_PROGRAMS = hello
hello_SOURCES = hello-common.c
EXTRA_hello_SOURCES = hello-linux.c hello-generic.c
hello_LDADD = $(HELLO_SYSTEM)
hello_DEPENDENCIES = $(HELLO_SYSTEM)
You can then setup the ‘$(HELLO_SYSTEM)’ substitution from configure.ac:
...
case $host in
*linux*) HELLO_SYSTEM=’hello-linux.$(OBJEXT)’ ;;
*) HELLO_SYSTEM=’hello-generic.$(OBJEXT)’ ;;
esac
AC_SUBST([HELLO_SYSTEM])
...
In this case, the variable HELLO_SYSTEM should be replaced by either hello-linux.o or
hello-generic.o, and added to both hello_DEPENDENCIES and hello_LDADD in order to
be built and linked in.
8.1.3.2 Conditional compilation using Automake conditionals
An often simpler way to compile source files conditionally is to use Automake conditionals.
For instance, you could use this Makefile.am construct to build the same hello example:
bin_PROGRAMS = hello
if LINUX
hello_SOURCES = hello-linux.c hello-common.c
else
hello_SOURCES = hello-generic.c hello-common.c
endif
Chapter 8: Building Programs and Libraries 54
In this case, configure.ac should setup the LINUX conditional using AM_CONDITIONAL
(see Chapter 20 [Conditionals], page 105).
When using conditionals like this you don’t need to use the EXTRA_ variable, because
Automake will examine the contents of each variable to construct the complete list of source
files.
If your program uses a lot of files, you will probably prefer a conditional ‘+=’.
bin_PROGRAMS = hello
hello_SOURCES = hello-common.c
if LINUX
hello_SOURCES += hello-linux.c
else
hello_SOURCES += hello-generic.c
endif
8.1.4 Conditional compilation of programs
Sometimes it is useful to determine the programs that are to be built at configure time.
For instance, GNU cpio only builds mt and rmt under special circumstances. The means
to achieve conditional compilation of programs are the same you can use to compile source
files conditionally: substitutions or conditionals.
8.1.4.1 Conditional programs using configure substitutions
In this case, you must notify Automake of all the programs that can possibly be built,
but at the same time cause the generated Makefile.in to use the programs specified by
configure. This is done by having configure substitute values into each _PROGRAMS
definition, while listing all optionally built programs in EXTRA_PROGRAMS.
bin_PROGRAMS = cpio pax $(MT)
libexec_PROGRAMS = $(RMT)
EXTRA_PROGRAMS = mt rmt
As explained in Section 8.19 [EXEEXT], page 78, Automake will rewrite bin_PROGRAMS,
libexec_PROGRAMS, and EXTRA_PROGRAMS, appending ‘$(EXEEXT)’ to each binary. Ob-
viously it cannot rewrite values obtained at run-time through configure substitutions,
therefore you should take care of appending ‘$(EXEEXT)’ yourself, as in ‘AC_SUBST([MT],
[’mt${EXEEXT}’])’.
8.1.4.2 Conditional programs using Automake conditionals
You can also use Automake conditionals (see Chapter 20 [Conditionals], page 105) to select
programs to be built. In this case you don’t have to worry about ‘$(EXEEXT)’ or EXTRA_
PROGRAMS.
bin_PROGRAMS = cpio pax
if WANT_MT
bin_PROGRAMS += mt
endif
if WANT_RMT
libexec_PROGRAMS = rmt
endif
Chapter 8: Building Programs and Libraries 55
8.2 Building a library
Building a library is much like building a program. In this case, the name of the primary
is LIBRARIES. Libraries can be installed in libdir or pkglibdir.
See Section 8.3 [A Shared Library], page 55, for information on how to build shared
libraries using libtool and the LTLIBRARIES primary.
Each _LIBRARIES variable is a list of the libraries to be built. For instance, to create a
library named libcpio.a, but not install it, you would write:
noinst_LIBRARIES = libcpio.a
libcpio_a_SOURCES = ...
The sources that go into a library are determined exactly as they are for programs,
via the _SOURCES variables. Note that the library name is canonicalized (see Section 3.4
[Canonicalization], page 21), so the _SOURCES variable corresponding to libcpio.a is
‘libcpio_a_SOURCES’, not ‘libcpio.a_SOURCES’.
Extra objects can be added to a library using the library_LIBADD variable. This should
be used for objects determined by configure. Again from cpio:
libcpio_a_LIBADD = $(LIBOBJS) $(ALLOCA)
In addition, sources for extra objects that will not exist until configure-time must be
added to the BUILT_SOURCES variable (see Section 9.4 [Sources], page 80).
Building a static library is done by compiling all object files, then by invoking ‘$(AR)
$(ARFLAGS)’ followed by the name of the library and the list of objects, and finally by calling
‘$(RANLIB)’ on that library. You should call AC_PROG_RANLIB from your configure.ac to
define RANLIB (Automake will complain otherwise). AR and ARFLAGS default to ar and cru
respectively; you can override these two variables my setting them in your Makefile.am, by
AC_SUBSTing them from your configure.ac, or by defining a per-library maude_AR variable
(see Section 8.4 [Program and Library Variables], page 62).
Be careful when selecting library components conditionally. Because building an empty
library is not portable, you should ensure that any library contains always at least one
object.
To use a static library when building a program, add it to LDADD for this program. In
the following example, the program cpio is statically linked with the library libcpio.a.
noinst_LIBRARIES = libcpio.a
libcpio_a_SOURCES = ...
bin_PROGRAMS = cpio
cpio_SOURCES = cpio.c ...
cpio_LDADD = libcpio.a
8.3 Building a Shared Library
Building shared libraries portably is a relatively complex matter. For this reason, GNU
Libtool (see Section “Introduction” in The Libtool Manual) was created to help build shared
libraries in a platform-independent way.
Chapter 8: Building Programs and Libraries 56
8.3.1 The Libtool Concept
Libtool abstracts shared and static libraries into a unified concept henceforth called libtool
libraries. Libtool libraries are files using the .la suffix, and can designate a static library, a
shared library, or maybe both. Their exact nature cannot be determined until ./configure
is run: not all platforms support all kinds of libraries, and users can explicitly select which
libraries should be built. (However the package’s maintainers can tune the default, see
Section “The AC_PROG_LIBTOOL macro” in The Libtool Manual.)
Because object files for shared and static libraries must be compiled differently, libtool
is also used during compilation. Object files built by libtool are called libtool objects: these
are files using the .lo suffix. Libtool libraries are built from these libtool objects.
You should not assume anything about the structure of .la or .lo files and how libtool
constructs them: this is libtool’s concern, and the last thing one wants is to learn about
libtool’s guts. However the existence of these files matters, because they are used as targets
and dependencies in Makefiles rules when building libtool libraries. There are situations
where you may have to refer to these, for instance when expressing dependencies for building
source files conditionally (see Section 8.3.4 [Conditional Libtool Sources], page 58).
People considering writing a plug-in system, with dynamically loaded modules, should
look into libltdl: libtool’s dlopening library (see Section “Using libltdl” in The Libtool
Manual). This offers a portable dlopening facility to load libtool libraries dynamically, and
can also achieve static linking where unavoidable.
Before we discuss how to use libtool with Automake in details, it should be noted that
the libtool manual also has a section about how to use Automake with libtool (see Section
“Using Automake with Libtool” in The Libtool Manual).
8.3.2 Building Libtool Libraries
Automake uses libtool to build libraries declared with the LTLIBRARIES primary. Each
_LTLIBRARIES variable is a list of libtool libraries to build. For instance, to create a libtool
library named libgettext.la, and install it in libdir, write:
lib_LTLIBRARIES = libgettext.la
libgettext_la_SOURCES = gettext.c gettext.h ...
Automake predefines the variable pkglibdir, so you can use pkglib_LTLIBRARIES to
install libraries in ‘$(libdir)/@PACKAGE@/’.
If gettext.h is a public header file that needs to be installed in order for people to
use the library, it should be declared using a _HEADERS variable, not in libgettext_la_
SOURCES. Headers listed in the latter should be internal headers that are not part of the
public interface.
lib_LTLIBRARIES = libgettext.la
libgettext_la_SOURCES = gettext.c ...
include_HEADERS = gettext.h ...
A package can build and install such a library along with other programs that use it.
This dependency should be specified using LDADD. The following example builds a program
named hello that is linked with libgettext.la.
lib_LTLIBRARIES = libgettext.la
libgettext_la_SOURCES = gettext.c ...
Chapter 8: Building Programs and Libraries 57
bin_PROGRAMS = hello
hello_SOURCES = hello.c ...
hello_LDADD = libgettext.la
Whether hello is statically or dynamically linked with libgettext.la is not yet known:
this will depend on the configuration of libtool and the capabilities of the host.
8.3.3 Building Libtool Libraries Conditionally
Like conditional programs (see Section 8.1.4 [Conditional Programs], page 54), there are two
main ways to build conditional libraries: using Automake conditionals or using Autoconf
AC_SUBSTitutions.
The important implementation detail you have to be aware of is that the place where a
library will be installed matters to libtool: it needs to be indicated at link-time using the
-rpath option.
For libraries whose destination directory is known when Automake runs, Automake will
automatically supply the appropriate -rpath option to libtool. This is the case for libraries
listed explicitly in some installable _LTLIBRARIES variables such as lib_LTLIBRARIES.
However, for libraries determined at configure time (and thus mentioned in EXTRA_
LTLIBRARIES), Automake does not know the final installation directory. For such libraries
you must add the -rpath option to the appropriate _LDFLAGS variable by hand.
The examples below illustrate the differences between these two methods.
Here is an example where WANTEDLIBS is an AC_SUBSTed variable set at ./configure-
time to either libfoo.la, libbar.la, both, or none. Although ‘$(WANTEDLIBS)’ appears
in the lib_LTLIBRARIES, Automake cannot guess it relates to libfoo.la or libbar.la by
the time it creates the link rule for these two libraries. Therefore the -rpath argument
must be explicitly supplied.
EXTRA_LTLIBRARIES = libfoo.la libbar.la
lib_LTLIBRARIES = $(WANTEDLIBS)
libfoo_la_SOURCES = foo.c ...
libfoo_la_LDFLAGS = -rpath ’$(libdir)’
libbar_la_SOURCES = bar.c ...
libbar_la_LDFLAGS = -rpath ’$(libdir)’
Here is how the same Makefile.am would look using Automake conditionals named
WANT_LIBFOO and WANT_LIBBAR. Now Automake is able to compute the -rpath setting
itself, because it’s clear that both libraries will end up in ‘$(libdir)’ if they are installed.
lib_LTLIBRARIES =
if WANT_LIBFOO
lib_LTLIBRARIES += libfoo.la
endif
if WANT_LIBBAR
lib_LTLIBRARIES += libbar.la
endif
libfoo_la_SOURCES = foo.c ...
libbar_la_SOURCES = bar.c ...
Chapter 8: Building Programs and Libraries 58
8.3.4 Libtool Libraries with Conditional Sources
Conditional compilation of sources in a library can be achieved in the same way as condi-
tional compilation of sources in a program (see Section 8.1.3 [Conditional Sources], page 53).
The only difference is that _LIBADD should be used instead of _LDADD and that it should
mention libtool objects (.lo files).
So, to mimic the hello example from Section 8.1.3 [Conditional Sources], page 53, we
could build a libhello.la library using either hello-linux.c or hello-generic.c with
the following Makefile.am.
lib_LTLIBRARIES = libhello.la
libhello_la_SOURCES = hello-common.c
EXTRA_libhello_la_SOURCES = hello-linux.c hello-generic.c
libhello_la_LIBADD = $(HELLO_SYSTEM)
libhello_la_DEPENDENCIES = $(HELLO_SYSTEM)
And make sure configure defines HELLO_SYSTEM as either hello-linux.lo or hello-
generic.lo.
Or we could simply use an Automake conditional as follows.
lib_LTLIBRARIES = libhello.la
libhello_la_SOURCES = hello-common.c
if LINUX
libhello_la_SOURCES += hello-linux.c
else
libhello_la_SOURCES += hello-generic.c
endif
8.3.5 Libtool Convenience Libraries
Sometimes you want to build libtool libraries that should not be installed. These are called
libtool convenience libraries and are typically used to encapsulate many sublibraries, later
gathered into one big installed library.
Libtool convenience libraries are declared by directory-less variables such as noinst_
LTLIBRARIES, check_LTLIBRARIES, or even EXTRA_LTLIBRARIES. Unlike installed libtool
libraries they do not need an -rpath flag at link time (actually this is the only difference).
Convenience libraries listed in noinst_LTLIBRARIES are always built. Those listed in
check_LTLIBRARIES are built only upon ‘make check’. Finally, libraries listed in EXTRA_
LTLIBRARIES are never built explicitly: Automake outputs rules to build them, but if the
library does not appear as a Makefile dependency anywhere it won’t be built (this is why
EXTRA_LTLIBRARIES is used for conditional compilation).
Here is a sample setup merging libtool convenience libraries from subdirectories into one
main libtop.la library.
# -- Top-level Makefile.am --
SUBDIRS = sub1 sub2 ...
lib_LTLIBRARIES = libtop.la
libtop_la_SOURCES =
libtop_la_LIBADD = \
sub1/libsub1.la \
Chapter 8: Building Programs and Libraries 59
sub2/libsub2.la \
...
# -- sub1/Makefile.am --
noinst_LTLIBRARIES = libsub1.la
libsub1_la_SOURCES = ...
# -- sub2/Makefile.am --
# showing nested convenience libraries
SUBDIRS = sub2.1 sub2.2 ...
noinst_LTLIBRARIES = libsub2.la
libsub2_la_SOURCES =
libsub2_la_LIBADD = \
sub21/libsub21.la \
sub22/libsub22.la \
...
When using such setup, beware that automake will assume libtop.la is to be linked
with the C linker. This is because libtop_la_SOURCES is empty, so automake picks C as
default language. If libtop_la_SOURCES was not empty, automake would select the linker
as explained in Section 8.13.3.1 [How the Linker is Chosen], page 75.
If one of the sublibraries contains non-C source, it is important that the appropriate
linker be chosen. One way to achieve this is to pretend that there is such a non-C file
among the sources of the library, thus forcing automake to select the appropriate linker.
Here is the top-level Makefile of our example updated to force C++ linking.
SUBDIRS = sub1 sub2 ...
lib_LTLIBRARIES = libtop.la
libtop_la_SOURCES =
# Dummy C++ source to cause C++ linking.
nodist_EXTRA_libtop_la_SOURCES = dummy.cxx
libtop_la_LIBADD = \
sub1/libsub1.la \
sub2/libsub2.la \
...
‘EXTRA_*_SOURCES’ variables are used to keep track of source files that might be compiled
(this is mostly useful when doing conditional compilation using AC_SUBST, see Section 8.3.4
[Conditional Libtool Sources], page 58), and the nodist_ prefix means the listed sources are
not to be distributed (see Section 8.4 [Program and Library Variables], page 62). In effect
the file dummy.cxx does not need to exist in the source tree. Of course if you have some real
source file to list in libtop_la_SOURCES there is no point in cheating with nodist_EXTRA_
libtop_la_SOURCES.
8.3.6 Libtool Modules
These are libtool libraries meant to be dlopened. They are indicated to libtool by passing
-module at link-time.
pkglib_LTLIBRARIES = mymodule.la
mymodule_la_SOURCES = doit.c
Chapter 8: Building Programs and Libraries 60
mymodule_la_LDFLAGS = -module
Ordinarily, Automake requires that a library’s name starts with lib. However, when
building a dynamically loadable module you might wish to use a "nonstandard" name.
Automake will not complain about such nonstandard name if it knows the library being
built is a libtool module, i.e., if -module explicitly appears in the library’s _LDFLAGS variable
(or in the common AM_LDFLAGS variable when no per-library _LDFLAGS variable is defined).
As always, AC_SUBST variables are black boxes to Automake since their values are not
yet known when automake is run. Therefore if -module is set via such a variable, Automake
cannot notice it and will proceed as if the library was an ordinary libtool library, with strict
naming.
If mymodule_la_SOURCES is not specified, then it defaults to the single file mymodule.c
(see Section 8.5 [Default SOURCES], page 65).
8.3.7 _LIBADD, _LDFLAGS, and _LIBTOOLFLAGS
As shown in previous sections, the ‘library_LIBADD’ variable should be used to list extra
libtool objects (.lo files) or libtool libraries (.la) to add to library.
The ‘library_LDFLAGS’ variable is the place to list additional libtool linking flags, such
as -version-info, -static, and a lot more. See Section “Link mode” in The Libtool
Manual.
The libtool command has two kinds of options: mode-specific options and generic
options. Mode-specific options such as the aforementioned linking flags should be
lumped with the other flags passed to the tool invoked by libtool (hence the use of
‘library_LDFLAGS’ for libtool linking flags). Generic options include --tag=TAG and
--silent (see Section “Invoking libtool” in The Libtool Manual for more options)
should appear before the mode selection on the command line; in Makefile.ams they
should be listed in the ‘library_LIBTOOLFLAGS’ variable.
If ‘library_LIBTOOLFLAGS’ is not defined, the global AM_LIBTOOLFLAGS variable is used
instead.
These flags are passed to libtool after the --tag=TAG option computed by Automake (if
any), so ‘library_LIBTOOLFLAGS’ (or AM_LIBTOOLFLAGS) is the good place to override or
supplement the --tag=TAG setting.
The libtool rules also use a LIBTOOLFLAGS variable that should not be set in
Makefile.am: this is a user variable (see Section 27.6 [Flag Variables Ordering], page 121.
It allows users to run ‘make LIBTOOLFLAGS=--silent’, for instance.
8.3.8 LTLIBOBJS and LTALLOCA
Where an ordinary library might include ‘$(LIBOBJS)’ or ‘$(ALLOCA)’ (see Section 8.6
[LIBOBJS], page 66), a libtool library must use ‘$(LTLIBOBJS)’ or ‘$(LTALLOCA)’. This is
required because the object files that libtool operates on do not necessarily end in .o.
Nowadays, the computation of LTLIBOBJS from LIBOBJS is performed automatically by
Autoconf (see Section “AC_LIBOBJ vs. LIBOBJS” in The Autoconf Manual).
8.3.9 Common Issues Related to Libtool’s Use
Chapter 8: Building Programs and Libraries 61
8.3.9.1 ‘required file ‘./ltmain.sh’ not found’
Libtool comes with a tool called libtoolize that will install libtool’s supporting files into
a package. Running this command will install ltmain.sh. You should execute it before
aclocal and automake.
People upgrading old packages to newer autotools are likely to face this issue because
older Automake versions used to call libtoolize. Therefore old build scripts do not call
libtoolize.
Since Automake 1.6, it has been decided that running libtoolize was none of Au-
tomake’s business. Instead, that functionality has been moved into the autoreconf com-
mand (see Section “Using autoreconf” in The Autoconf Manual). If you do not want to
remember what to run and when, just learn the autoreconf command. Hopefully, replacing
existing bootstrap.sh or autogen.sh scripts by a call to autoreconf should also free you
from any similar incompatible change in the future.
8.3.9.2 Objects ‘created with both libtool and without’
Sometimes, the same source file is used both to build a libtool library and to build another
non-libtool target (be it a program or another library).
Let’s consider the following Makefile.am.
bin_PROGRAMS = prog
prog_SOURCES = prog.c foo.c ...
lib_LTLIBRARIES = libfoo.la
libfoo_la_SOURCES = foo.c ...
(In this trivial case the issue could be avoided by linking libfoo.la with prog instead of
listing foo.c in prog_SOURCES. But let’s assume we really want to keep prog and libfoo.la
separate.)
Technically, it means that we should build foo.$(OBJEXT) for prog, and foo.lo for
libfoo.la. The problem is that in the course of creating foo.lo, libtool may erase (or
replace) foo.$(OBJEXT), and this cannot be avoided.
Therefore, when Automake detects this situation it will complain with a message such
as
object ‘foo.$(OBJEXT)’ created both with libtool and without
A workaround for this issue is to ensure that these two objects get different basenames.
As explained in Section 27.7 [renamed objects], page 124, this happens automatically when
per-targets flags are used.
bin_PROGRAMS = prog
prog_SOURCES = prog.c foo.c ...
prog_CFLAGS = $(AM_CFLAGS)
lib_LTLIBRARIES = libfoo.la
libfoo_la_SOURCES = foo.c ...
Adding ‘prog_CFLAGS = $(AM_CFLAGS)’ is almost a no-op, because when the prog_CFLAGS
is defined, it is used instead of AM_CFLAGS. However as a side effect it will cause prog.c and
Chapter 8: Building Programs and Libraries 62
foo.c to be compiled as prog-prog.$(OBJEXT) and prog-foo.$(OBJEXT), which solves
the issue.
8.4 Program and Library Variables
Associated with each program are a collection of variables that can be used to modify how
that program is built. There is a similar list of such variables for each library. The canonical
name of the program (or library) is used as a base for naming these variables.
In the list below, we use the name “maude” to refer to the program or library. In your
Makefile.am you would replace this with the canonical name of your program. This list
also refers to “maude” as a program, but in general the same rules apply for both static and
dynamic libraries; the documentation below notes situations where programs and libraries
differ.
maude_SOURCES
This variable, if it exists, lists all the source files that are compiled to build the
program. These files are added to the distribution by default. When building
the program, Automake will cause each source file to be compiled to a single .o
file (or .lo when using libtool). Normally these object files are named after the
source file, but other factors can change this. If a file in the _SOURCES variable
has an unrecognized extension, Automake will do one of two things with it. If a
suffix rule exists for turning files with the unrecognized extension into .o files,
then automake will treat this file as it will any other source file (see Section 8.16
[Support for Other Languages], page 76). Otherwise, the file will be ignored as
though it were a header file.
The prefixes dist_ and nodist_ can be used to control whether files listed
in a _SOURCES variable are distributed. dist_ is redundant, as sources are
distributed by default, but it can be specified for clarity if desired.
It is possible to have both dist_ and nodist_ variants of a given _SOURCES
variable at once; this lets you easily distribute some files and not others, for
instance:
nodist_maude_SOURCES = nodist.c
dist_maude_SOURCES = dist-me.c
By default the output file (on Unix systems, the .o file) will be put into the cur-
rent build directory. However, if the option subdir-objects is in effect in the
current directory then the .o file will be put into the subdirectory named after
the source file. For instance, with subdir-objects enabled, sub/dir/file.c
will be compiled to sub/dir/file.o. Some people prefer this mode of opera-
tion. You can specify subdir-objects in AUTOMAKE_OPTIONS (see Chapter 17
[Options], page 99).
EXTRA_maude_SOURCES
Automake needs to know the list of files you intend to compile statically. For
one thing, this is the only way Automake has of knowing what sort of language
support a given Makefile.in requires.4 This means that, for example, you can’t
4
There are other, more obscure reasons for this limitation as well.
Chapter 8: Building Programs and Libraries 63
put a configure substitution like ‘@my_sources@’ into a ‘_SOURCES’ variable. If
you intend to conditionally compile source files and use configure to substitute
the appropriate object names into, e.g., _LDADD (see below), then you should
list the corresponding source files in the EXTRA_ variable.
This variable also supports dist_ and nodist_ prefixes. For instance, nodist_
EXTRA_maude_SOURCES would list extra sources that may need to be built, but
should not be distributed.
maude_AR A static library is created by default by invoking ‘$(AR) $(ARFLAGS)’ followed
by the name of the library and then the objects being put into the library. You
can override this by setting the _AR variable. This is usually used with C++;
some C++ compilers require a special invocation in order to instantiate all the
templates that should go into a library. For instance, the SGI C++ compiler
likes this variable set like so:
libmaude_a_AR = $(CXX) -ar -o
maude_LIBADD
Extra objects can be added to a library using the _LIBADD variable. For in-
stance, this should be used for objects determined by configure (see Section 8.2
[A Library], page 55).
In the case of libtool libraries, maude_LIBADD can also refer to other libtool
libraries.
maude_LDADD
Extra objects (*.$(OBJEXT)) and libraries (*.a, *.la) can be added to a pro-
gram by listing them in the _LDADD variable. For instance, this should be used
for objects determined by configure (see Section 8.1.2 [Linking], page 52).
_LDADD and _LIBADD are inappropriate for passing program-specific linker flags
(except for -l, -L, -dlopen and -dlpreopen). Use the _LDFLAGS variable for
this purpose.
For instance, if your configure.ac uses AC_PATH_XTRA, you could link your
program against the X libraries like so:
maude_LDADD = $(X_PRE_LIBS) $(X_LIBS) $(X_EXTRA_LIBS)
We recommend that you use -l and -L only when referring to third-party
libraries, and give the explicit file names of any library built by your package.
Doing so will ensure that maude_DEPENDENCIES (see below) is correctly defined
by default.
maude_LDFLAGS
This variable is used to pass extra flags to the link step of a program or a shared
library. It overrides the global AM_LDFLAGS variable.
maude_LIBTOOLFLAGS
This variable is used to pass extra options to libtool. It overrides the
global AM_LIBTOOLFLAGS variable. These options are output before libtool’s
--mode=MODE option, so they should not be mode-specific options (those belong
to the compiler or linker flags). See Section 8.3.7 [Libtool Flags], page 60.
Chapter 8: Building Programs and Libraries 64
maude_DEPENDENCIES
It is also occasionally useful to have a target (program or library) depend on
some other file that is not actually part of that target. This can be done using
the _DEPENDENCIES variable. Each targets depends on the contents of such a
variable, but no further interpretation is done.
Since these dependencies are associated to the link rule used to create the
programs they should normally list files used by the link command. That is
*.$(OBJEXT), *.a, or *.la files for programs; *.lo and *.la files for Libtool
libraries; and *.$(OBJEXT) files for static libraries. In rare cases you may need
to add other kinds of files such as linker scripts, but listing a source file in
_DEPENDENCIES is wrong. If some source file needs to be built before all the
components of a program are built, consider using the BUILT_SOURCES variable
(see Section 9.4 [Sources], page 80).
If _DEPENDENCIES is not supplied, it is computed by Automake. The
automatically-assigned value is the contents of _LDADD or _LIBADD, with most
configure substitutions, -l, -L, -dlopen and -dlpreopen options removed.
The configure substitutions that are left in are only ‘$(LIBOBJS)’ and
‘$(ALLOCA)’; these are left because it is known that they will not cause an
invalid value for _DEPENDENCIES to be generated.
_DEPENDENCIES is more likely used to perform conditional compilation using an
AC_SUBST variable that contains a list of objects. See Section 8.1.3 [Conditional
Sources], page 53, and Section 8.3.4 [Conditional Libtool Sources], page 58.
maude_LINK
You can override the linker on a per-program basis. By default the linker is
chosen according to the languages used by the program. For instance, a program
that includes C++ source code would use the C++ compiler to link. The _LINK
variable must hold the name of a command that can be passed all the .o file
names as arguments. Note that the name of the underlying program is not
passed to _LINK; typically one uses ‘$@’:
maude_LINK = $(CCLD) -magic -o $@
maude_CCASFLAGS
maude_CFLAGS
maude_CPPFLAGS
maude_CXXFLAGS
maude_FFLAGS
maude_GCJFLAGS
maude_LFLAGS
maude_OBJCFLAGS
maude_RFLAGS
maude_UPCFLAGS
maude_YFLAGS
Automake allows you to set compilation flags on a per-program (or per-library)
basis. A single source file can be included in several programs, and it will poten-
tially be compiled with different flags for each program. This works for any lan-
guage directly supported by Automake. These per-target compilation flags are
Chapter 8: Building Programs and Libraries 65
‘_CCASFLAGS’, ‘_CFLAGS’, ‘_CPPFLAGS’, ‘_CXXFLAGS’, ‘_FFLAGS’, ‘_GCJFLAGS’,
‘_LFLAGS’, ‘_OBJCFLAGS’, ‘_RFLAGS’, ‘_UPCFLAGS’, and ‘_YFLAGS’.
When using a per-target compilation flag, Automake will choose a different
name for the intermediate object files. Ordinarily a file like sample.c will be
compiled to produce sample.o. However, if the program’s _CFLAGS variable is
set, then the object file will be named, for instance, maude-sample.o. (See also
Section 27.7 [renamed objects], page 124.) The use of per-target compilation
flags with C sources requires that the macro AM_PROG_CC_C_O be called from
configure.ac.
In compilations with per-target flags, the ordinary ‘AM_’ form of the flags vari-
able is not automatically included in the compilation (however, the user form
of the variable is included). So for instance, if you want the hypothetical maude
compilations to also use the value of AM_CFLAGS, you would need to write:
maude_CFLAGS = ... your flags ... $(AM_CFLAGS)
See Section 27.6 [Flag Variables Ordering], page 121, for more discussion about
the interaction between user variables, ‘AM_’ shadow variables, and per-target
variables.
maude_SHORTNAME
On some platforms the allowable file names are very short. In order to support
these systems and per-target compilation flags at the same time, Automake
allows you to set a “short name” that will influence how intermediate object
files are named. For instance, in the following example,
bin_PROGRAMS = maude
maude_CPPFLAGS = -DSOMEFLAG
maude_SHORTNAME = m
maude_SOURCES = sample.c ...
the object file would be named m-sample.o rather than maude-sample.o.
This facility is rarely needed in practice, and we recommend avoiding it until
you find it is required.
8.5 Default _SOURCES
_SOURCES variables are used to specify source files of programs (see Section 8.1 [A Pro-
gram], page 51), libraries (see Section 8.2 [A Library], page 55), and Libtool libraries (see
Section 8.3 [A Shared Library], page 55).
When no such variable is specified for a target, Automake will define one itself. The
default is to compile a single C file whose base name is the name of the target itself, with
any extension replaced by .c. (Defaulting to C is terrible but we are stuck with it for
historical reasons.)
For example if you have the following somewhere in your Makefile.am with no corre-
sponding libfoo_a_SOURCES:
lib_LIBRARIES = libfoo.a sub/libc++.a
libfoo.a will be built using a default source file named libfoo.c, and sub/libc++.a
will be built from sub/libc++.c. (In older versions sub/libc++.a would be built from
Chapter 8: Building Programs and Libraries 66
sub_libc___a.c, i.e., the default source was the canonized name of the target, with .c
appended. We believe the new behavior is more sensible, but for backward compatibility
automake will use the old name if a file or a rule with that name exist.)
Default sources are mainly useful in test suites, when building many tests programs each
from a single source. For instance, in
check_PROGRAMS = test1 test2 test3
test1, test2, and test3 will be built from test1.c, test2.c, and test3.c.
Another case where is this convenient is building many Libtool modules (moduleN.la),
each defined in its own file (moduleN.c).
AM_LDFLAGS = -module
lib_LTLIBRARIES = module1.la module2.la module3.la
Finally, there is one situation where this default source computation needs to be avoided:
when a target should not be built from sources. We already saw such an example in
Section 4.2 [true], page 24; this happens when all the constituents of a target have already
been compiled and need just to be combined using a _LDADD variable. Then it is necessary
to define an empty _SOURCES variable, so that automake does not compute a default.
bin_PROGRAMS = target
target_SOURCES =
target_LDADD = libmain.a libmisc.a
8.6 Special handling for LIBOBJS and ALLOCA
The ‘$(LIBOBJS)’ and ‘$(ALLOCA)’ variables list object files that should be compiled into
the project to provide an implementation for functions that are missing or broken on the
host system. They are substituted by configure.
These variables are defined by Autoconf macros such as AC_LIBOBJ, AC_REPLACE_FUNCS
(see Section “Generic Function Checks” in The Autoconf Manual), or AC_FUNC_ALLOCA (see
Section “Particular Function Checks” in The Autoconf Manual). Many other Autoconf
macros call AC_LIBOBJ or AC_REPLACE_FUNCS to populate ‘$(LIBOBJS)’.
Using these variables is very similar to doing conditional compilation using AC_SUBST
variables, as described in Section 8.1.3 [Conditional Sources], page 53. That is, when build-
ing a program, ‘$(LIBOBJS)’ and ‘$(ALLOCA)’ should be added to the associated ‘*_LDADD’
variable, or to the ‘*_LIBADD’ variable when building a library. However there is no need
to list the corresponding sources in ‘EXTRA_*_SOURCES’ nor to define ‘*_DEPENDENCIES’.
Automake automatically adds ‘$(LIBOBJS)’ and ‘$(ALLOCA)’ to the dependencies, and it
will discover the list of corresponding source files automatically (by tracing the invocations
of the AC_LIBSOURCE Autoconf macros).
These variables are usually used to build a portability library that is linked with all the
programs of the project. We now review a sample setup. First, configure.ac contains
some checks that affect either LIBOBJS or ALLOCA.
# configure.ac
...
AC_CONFIG_LIBOBJ_DIR([lib])
...
AC_FUNC_MALLOC dnl May add malloc.$(OBJEXT) to LIBOBJS
Chapter 8: Building Programs and Libraries 67
AC_FUNC_MEMCMP dnl May add memcmp.$(OBJEXT) to LIBOBJS
AC_REPLACE_FUNCS([strdup]) dnl May add strdup.$(OBJEXT) to LIBOBJS
AC_FUNC_ALLOCA dnl May add alloca.$(OBJEXT) to ALLOCA
...
AC_CONFIG_FILES([
lib/Makefile
src/Makefile
])
AC_OUTPUT
The AC_CONFIG_LIBOBJ_DIR tells Autoconf that the source files of these object files are
to be found in the lib/ directory. Automake can also use this information, otherwise it
expects the source files are to be in the directory where the ‘$(LIBOBJS)’ and ‘$(ALLOCA)’
variables are used.
The lib/ directory should therefore contain malloc.c, memcmp.c, strdup.c, alloca.c.
Here is its Makefile.am:
# lib/Makefile.am
noinst_LIBRARIES = libcompat.a
libcompat_a_SOURCES =
libcompat_a_LIBADD = $(LIBOBJS) $(ALLOCA)
The library can have any name, of course, and anyway it is not going to be installed:
it just holds the replacement versions of the missing or broken functions so we can later
link them in. In many projects also include extra functions, specific to the project, in that
library: they are simply added on the _SOURCES line.
There is a small trap here, though: ‘$(LIBOBJS)’ and ‘$(ALLOCA)’ might be empty, and
building an empty library is not portable. You should ensure that there is always something
to put in libcompat.a. Most projects will also add some utility functions in that directory,
and list them in libcompat_a_SOURCES, so in practice libcompat.a cannot be empty.
Finally here is how this library could be used from the src/ directory.
# src/Makefile.am
# Link all programs in this directory with libcompat.a
LDADD = ../lib/libcompat.a
bin_PROGRAMS = tool1 tool2 ...
tool1_SOURCES = ...
tool2_SOURCES = ...
When option subdir-objects is not used, as in the above example, the variables
‘$(LIBOBJS)’ or ‘$(ALLOCA)’ can only be used in the directory where their sources lie.
E.g., here it would be wrong to use ‘$(LIBOBJS)’ or ‘$(ALLOCA)’ in src/Makefile.am.
However if both subdir-objects and AC_CONFIG_LIBOBJ_DIR are used, it is OK to use
these variables in other directories. For instance src/Makefile.am could be changed as
follows.
# src/Makefile.am
Chapter 8: Building Programs and Libraries 68
AUTOMAKE_OPTIONS = subdir-objects
LDADD = $(LIBOBJS) $(ALLOCA)
bin_PROGRAMS = tool1 tool2 ...
tool1_SOURCES = ...
tool2_SOURCES = ...
Because ‘$(LIBOBJS)’ and ‘$(ALLOCA)’ contain object file names that end with
‘.$(OBJEXT)’, they are not suitable for Libtool libraries (where the expected object
extension is .lo): LTLIBOBJS and LTALLOCA should be used instead.
LTLIBOBJS is defined automatically by Autoconf and should not be defined by hand (as
in the past), however at the time of writing LTALLOCA still needs to be defined from ALLOCA
manually. See Section “AC_LIBOBJ vs. LIBOBJS” in The Autoconf Manual.
8.7 Variables used when building a program
Occasionally it is useful to know which Makefile variables Automake uses for compilations;
for instance, you might need to do your own compilation in some special cases.
Some variables are inherited from Autoconf; these are CC, CFLAGS, CPPFLAGS, DEFS,
LDFLAGS, and LIBS.
There are some additional variables that Automake defines on its own:
AM_CPPFLAGS
The contents of this variable are passed to every compilation that invokes the
C preprocessor; it is a list of arguments to the preprocessor. For instance, -I
and -D options should be listed here.
Automake already provides some -I options automatically, in a separate vari-
able that is also passed to every compilation that invokes the C preprocessor. In
particular it generates ‘-I.’, ‘-I$(srcdir)’, and a -I pointing to the directory
holding config.h (if you’ve used AC_CONFIG_HEADERS or AM_CONFIG_HEADER).
You can disable the default -I options using the nostdinc option.
AM_CPPFLAGS is ignored in preference to a per-executable (or per-library) _
CPPFLAGS variable if it is defined.
INCLUDES This does the same job as AM_CPPFLAGS (or any per-target _CPPFLAGS variable
if it is used). It is an older name for the same functionality. This variable is
deprecated; we suggest using AM_CPPFLAGS and per-target _CPPFLAGS instead.
AM_CFLAGS
This is the variable the Makefile.am author can use to pass in additional C
compiler flags. It is more fully documented elsewhere. In some situations, this
is not used, in preference to the per-executable (or per-library) _CFLAGS.
COMPILE This is the command used to actually compile a C source file. The file name is
appended to form the complete command line.
AM_LDFLAGS
This is the variable the Makefile.am author can use to pass in additional linker
flags. In some situations, this is not used, in preference to the per-executable
(or per-library) _LDFLAGS.
Chapter 8: Building Programs and Libraries 69
LINK This is the command used to actually link a C program. It already includes
‘-o $@’ and the usual variable references (for instance, CFLAGS); it takes as
“arguments” the names of the object files and libraries to link in.
8.8 Yacc and Lex support
Automake has somewhat idiosyncratic support for Yacc and Lex.
Automake assumes that the .c file generated by yacc (or lex) should be named using
the basename of the input file. That is, for a yacc source file foo.y, Automake will cause
the intermediate file to be named foo.c (as opposed to y.tab.c, which is more traditional).
The extension of a yacc source file is used to determine the extension of the resulting
C or C++ file. Files with the extension .y will be turned into .c files; likewise, .yy will
become .cc; .y++, c++; .yxx, .cxx; and .ypp, .cpp.
Likewise, lex source files can be used to generate C or C++; the extensions .l, .ll, .l++,
.lxx, and .lpp are recognized.
You should never explicitly mention the intermediate (C or C++) file in any SOURCES
variable; only list the source file.
The intermediate files generated by yacc (or lex) will be included in any distribution
that is made. That way the user doesn’t need to have yacc or lex.
If a yacc source file is seen, then your configure.ac must define the variable YACC. This
is most easily done by invoking the macro AC_PROG_YACC (see Section “Particular Program
Checks” in The Autoconf Manual).
When yacc is invoked, it is passed YFLAGS and AM_YFLAGS. The former is a user variable
and the latter is intended for the Makefile.am author.
AM_YFLAGS is usually used to pass the -d option to yacc. Automake knows what this
means and will automatically adjust its rules to update and distribute the header file built
by ‘yacc -d’. What Automake cannot guess, though, is where this header will be used: it is
up to you to ensure the header gets built before it is first used. Typically this is necessary
in order for dependency tracking to work when the header is included by another file. The
common solution is listing the header file in BUILT_SOURCES (see Section 9.4 [Sources],
page 80) as follows.
BUILT_SOURCES = parser.h
AM_YFLAGS = -d
bin_PROGRAMS = foo
foo_SOURCES = ... parser.y ...
If a lex source file is seen, then your configure.ac must define the variable LEX. You
can use AC_PROG_LEX to do this (see Section “Particular Program Checks” in The Autoconf
Manual), but using AM_PROG_LEX macro (see Section 6.4 [Macros], page 42) is recommended.
When lex is invoked, it is passed LFLAGS and AM_LFLAGS. The former is a user variable
and the latter is intended for the Makefile.am author.
When AM_MAINTAINER_MODE (see Section 27.2 [maintainer-mode], page 117) is used, the
rebuild rule for distributed Yacc and Lex sources are only used when maintainer-mode is
enabled, or when the files have been erased.
When lex or yacc sources are used, automake -i automatically installs an auxiliary
program called ylwrap in your package (see Section 3.6 [Auxiliary Programs], page 21).
Chapter 8: Building Programs and Libraries 70
This program is used by the build rules to rename the output of these tools, and makes
it possible to include multiple yacc (or lex) source files in a single directory. (This is
necessary because yacc’s output file name is fixed, and a parallel make could conceivably
invoke more than one instance of yacc simultaneously.)
For yacc, simply managing locking is insufficient. The output of yacc always uses the
same symbol names internally, so it isn’t possible to link two yacc parsers into the same
executable.
We recommend using the following renaming hack used in gdb:
#define yymaxdepth c_maxdepth
#define yyparse c_parse
#define yylex c_lex
#define yyerror c_error
#define yylval c_lval
#define yychar c_char
#define yydebug c_debug
#define yypact c_pact
#define yyr1 c_r1
#define yyr2 c_r2
#define yydef c_def
#define yychk c_chk
#define yypgo c_pgo
#define yyact c_act
#define yyexca c_exca
#define yyerrflag c_errflag
#define yynerrs c_nerrs
#define yyps c_ps
#define yypv c_pv
#define yys c_s
#define yy_yys c_yys
#define yystate c_state
#define yytmp c_tmp
#define yyv c_v
#define yy_yyv c_yyv
#define yyval c_val
#define yylloc c_lloc
#define yyreds c_reds
#define yytoks c_toks
#define yylhs c_yylhs
#define yylen c_yylen
#define yydefred c_yydefred
#define yydgoto c_yydgoto
#define yysindex c_yysindex
#define yyrindex c_yyrindex
#define yygindex c_yygindex
#define yytable c_yytable
#define yycheck c_yycheck
Chapter 8: Building Programs and Libraries 71
#define yyname c_yyname
#define yyrule c_yyrule
For each define, replace the ‘c_’ prefix with whatever you like. These defines work for
bison, byacc, and traditional yaccs. If you find a parser generator that uses a symbol not
covered here, please report the new name so it can be added to the list.
8.9 C++ Support
Automake includes full support for C++.
Any package including C++ code must define the output variable CXX in configure.ac;
the simplest way to do this is to use the AC_PROG_CXX macro (see Section “Particular
Program Checks” in The Autoconf Manual).
A few additional variables are defined when a C++ source file is seen:
CXX The name of the C++ compiler.
CXXFLAGS Any flags to pass to the C++ compiler.
AM_CXXFLAGS
The maintainer’s variant of CXXFLAGS.
CXXCOMPILE
The command used to actually compile a C++ source file. The file name is
appended to form the complete command line.
CXXLINK The command used to actually link a C++ program.
8.10 Objective C Support
Automake includes some support for Objective C.
Any package including Objective C code must define the output variable OBJC in
configure.ac; the simplest way to do this is to use the AC_PROG_OBJC macro (see Section
“Particular Program Checks” in The Autoconf Manual).
A few additional variables are defined when an Objective C source file is seen:
OBJC The name of the Objective C compiler.
OBJCFLAGS
Any flags to pass to the Objective C compiler.
AM_OBJCFLAGS
The maintainer’s variant of OBJCFLAGS.
OBJCCOMPILE
The command used to actually compile a Objective C source file. The file name
is appended to form the complete command line.
OBJCLINK The command used to actually link a Objective C program.
Chapter 8: Building Programs and Libraries 72
8.11 Unified Parallel C Support
Automake includes some support for Unified Parallel C.
Any package including Unified Parallel C code must define the output variable UPC
in configure.ac; the simplest way to do this is to use the AM_PROG_UPC macro (see
Section 6.4.1 [Public macros], page 42).
A few additional variables are defined when an Unified Parallel C source file is seen:
UPC The name of the Unified Parallel C compiler.
UPCFLAGS Any flags to pass to the Unified Parallel C compiler.
AM_UPCFLAGS
The maintainer’s variant of UPCFLAGS.
UPCCOMPILE
The command used to actually compile a Unified Parallel C source file. The
file name is appended to form the complete command line.
UPCLINK The command used to actually link a Unified Parallel C program.
8.12 Assembly Support
Automake includes some support for assembly code. There are two forms of assembler files:
normal (*.s) and preprocessed by CPP (*.S or *.sx).
The variable CCAS holds the name of the compiler used to build assembly code. This com-
piler must work a bit like a C compiler; in particular it must accept -c and -o. The values
of CCASFLAGS and AM_CCASFLAGS (or its per-target definition) is passed to the compilation.
For preprocessed files, DEFS, DEFAULT_INCLUDES, INCLUDES, CPPFLAGS and AM_CPPFLAGS
are also used.
The autoconf macro AM_PROG_AS will define CCAS and CCASFLAGS for you (unless they
are already set, it simply sets CCAS to the C compiler and CCASFLAGS to the C compiler
flags), but you are free to define these variables by other means.
Only the suffixes .s, .S, and .sx are recognized by automake as being files containing
assembly code.
8.13 Fortran 77 Support
Automake includes full support for Fortran 77.
Any package including Fortran 77 code must define the output variable F77 in
configure.ac; the simplest way to do this is to use the AC_PROG_F77 macro (see Section
“Particular Program Checks” in The Autoconf Manual).
A few additional variables are defined when a Fortran 77 source file is seen:
F77 The name of the Fortran 77 compiler.
FFLAGS Any flags to pass to the Fortran 77 compiler.
AM_FFLAGS
The maintainer’s variant of FFLAGS.
RFLAGS Any flags to pass to the Ratfor compiler.
Chapter 8: Building Programs and Libraries 73
AM_RFLAGS
The maintainer’s variant of RFLAGS.
F77COMPILE
The command used to actually compile a Fortran 77 source file. The file name
is appended to form the complete command line.
FLINK The command used to actually link a pure Fortran 77 program or shared library.
Automake can handle preprocessing Fortran 77 and Ratfor source files in addition to
compiling them5 . Automake also contains some support for creating programs and shared
libraries that are a mixture of Fortran 77 and other languages (see Section 8.13.3 [Mixing
Fortran 77 With C and C++], page 73).
These issues are covered in the following sections.
8.13.1 Preprocessing Fortran 77
N.f is made automatically from N.F or N.r. This rule runs just the preprocessor to convert
a preprocessable Fortran 77 or Ratfor source file into a strict Fortran 77 source file. The
precise command used is as follows:
.F $(F77) -F $(DEFS) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS)
$(AM_FFLAGS) $(FFLAGS)
.r $(F77) -F $(AM_FFLAGS) $(FFLAGS) $(AM_RFLAGS) $(RFLAGS)
8.13.2 Compiling Fortran 77 Files
N.o is made automatically from N.f, N.F or N.r by running the Fortran 77 compiler. The
precise command used is as follows:
.f $(F77) -c $(AM_FFLAGS) $(FFLAGS)
.F $(F77) -c $(DEFS) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS)
$(AM_FFLAGS) $(FFLAGS)
.r $(F77) -c $(AM_FFLAGS) $(FFLAGS) $(AM_RFLAGS) $(RFLAGS)
8.13.3 Mixing Fortran 77 With C and C++
Automake currently provides limited support for creating programs and shared libraries
that are a mixture of Fortran 77 and C and/or C++. However, there are many other issues
related to mixing Fortran 77 with other languages that are not (currently) handled by
Automake, but that are handled by other packages6 .
5
Much, if not most, of the information in the following sections pertaining to preprocessing Fortran 77
programs was taken almost verbatim from Section “Catalogue of Rules” in The GNU Make Manual.
6
For example, the cfortran package (http://www-zeus.desy.de/~burow/cfortran/) addresses all of these
inter-language issues, and runs under nearly all Fortran 77, C and C++ compilers on nearly all platforms.
However, cfortran is not yet Free Software, but it will be in the next major release.
Chapter 8: Building Programs and Libraries 74
Automake can help in two ways:
1. Automatic selection of the linker depending on which combinations of source code.
2. Automatic selection of the appropriate linker flags (e.g., -L and -l) to pass to the
automatically selected linker in order to link in the appropriate Fortran 77 intrinsic
and run-time libraries.
These extra Fortran 77 linker flags are supplied in the output variable FLIBS by the
AC_F77_LIBRARY_LDFLAGS Autoconf macro supplied with newer versions of Autoconf
(Autoconf version 2.13 and later). See Section “Fortran 77 Compiler Characteristics”
in The Autoconf .
If Automake detects that a program or shared library (as mentioned in some _PROGRAMS
or _LTLIBRARIES primary) contains source code that is a mixture of Fortran 77 and C and/or
C++, then it requires that the macro AC_F77_LIBRARY_LDFLAGS be called in configure.ac,
and that either $(FLIBS) appear in the appropriate _LDADD (for programs) or _LIBADD (for
shared libraries) variables. It is the responsibility of the person writing the Makefile.am
to make sure that ‘$(FLIBS)’ appears in the appropriate _LDADD or _LIBADD variable.
For example, consider the following Makefile.am:
bin_PROGRAMS = foo
foo_SOURCES = main.cc foo.f
foo_LDADD = libfoo.la $(FLIBS)
pkglib_LTLIBRARIES = libfoo.la
libfoo_la_SOURCES = bar.f baz.c zardoz.cc
libfoo_la_LIBADD = $(FLIBS)
In this case, Automake will insist that AC_F77_LIBRARY_LDFLAGS is mentioned
in configure.ac. Also, if ‘$(FLIBS)’ hadn’t been mentioned in foo_LDADD and
libfoo_la_LIBADD, then Automake would have issued a warning.
Chapter 8: Building Programs and Libraries 75
8.13.3.1 How the Linker is Chosen
When a program or library mixes several languages, Automake choose the linker according
to the following priorities. (The names in parentheses are the variables containing the link
command.)
1. Native Java (GCJLINK)
2. C++ (CXXLINK)
3. Fortran 77 (F77LINK)
4. Fortran (FCLINK)
5. Objective C (OBJCLINK)
6. Unified Parallel C (UPCLINK)
7. C (LINK)
For example, if Fortran 77, C and C++ source code is compiled into a program, then the
C++ linker will be used. In this case, if the C or Fortran 77 linkers required any special
libraries that weren’t included by the C++ linker, then they must be manually added to an
_LDADD or _LIBADD variable by the user writing the Makefile.am.
Automake only looks at the file names listed in _SOURCES variables to choose the linker,
and defaults to the C linker. Sometimes this is inconvenient because you are linking against
a library written in another language and would like to set the linker more appropriately.
See Section 8.3.5 [Libtool Convenience Libraries], page 58, for a trick with nodist_EXTRA_
..._SOURCES.
8.14 Fortran 9x Support
Automake includes support for Fortran 9x.
Any package including Fortran 9x code must define the output variable FC in
configure.ac; the simplest way to do this is to use the AC_PROG_FC macro (see Section
“Particular Program Checks” in The Autoconf Manual).
A few additional variables are defined when a Fortran 9x source file is seen:
FC The name of the Fortran 9x compiler.
FCFLAGS Any flags to pass to the Fortran 9x compiler.
AM_FCFLAGS
The maintainer’s variant of FCFLAGS.
FCCOMPILE
The command used to actually compile a Fortran 9x source file. The file name
is appended to form the complete command line.
FCLINK The command used to actually link a pure Fortran 9x program or shared library.
8.14.1 Compiling Fortran 9x Files
N.o is made automatically from N.f90, N.f95, N.f03, or N.f08 by running the Fortran 9x
compiler. The precise command used is as follows:
.f90 $(FC) $(AM_FCFLAGS) $(FCFLAGS) -c $(FCFLAGS_f90) $<
Chapter 8: Building Programs and Libraries 76
.f95 $(FC) $(AM_FCFLAGS) $(FCFLAGS) -c $(FCFLAGS_f95) $<
.f03 $(FC) $(AM_FCFLAGS) $(FCFLAGS) -c $(FCFLAGS_f03) $<
.f08 $(FC) $(AM_FCFLAGS) $(FCFLAGS) -c $(FCFLAGS_f08) $<
8.15 Java Support
Automake includes support for compiled Java, using gcj, the Java front end to the GNU
Compiler Collection.
Any package including Java code to be compiled must define the output variable
GCJ in configure.ac; the variable GCJFLAGS must also be defined somehow (either in
configure.ac or Makefile.am). The simplest way to do this is to use the AM_PROG_GCJ
macro.
By default, programs including Java source files are linked with gcj.
As always, the contents of AM_GCJFLAGS are passed to every compilation invoking gcj (in
its role as an ahead-of-time compiler, when invoking it to create .class files, AM_JAVACFLAGS
is used instead). If it is necessary to pass options to gcj from Makefile.am, this variable,
and not the user variable GCJFLAGS, should be used.
gcj can be used to compile .java, .class, .zip, or .jar files.
When linking, gcj requires that the main class be specified using the --main= option.
The easiest way to do this is to use the _LDFLAGS variable for the program.
8.16 Support for Other Languages
Automake currently only includes full support for C, C++ (see Section 8.9 [C++ Support],
page 71), Objective C (see Section 8.10 [Objective C Support], page 71), Fortran 77 (see
Section 8.13 [Fortran 77 Support], page 72), Fortran 9x (see Section 8.14 [Fortran 9x Sup-
port], page 75), and Java (see Section 8.15 [Java Support], page 76). There is only rudi-
mentary support for other languages, support for which will be improved based on user
demand.
Some limited support for adding your own languages is available via the suffix rule
handling (see Section 18.2 [Suffixes], page 104).
8.17 Automatic de-ANSI-fication
The features described in this section are obsolete; you should not used any of them in new
code, and they may be withdrawn in future Automake releases.
When the C language was standardized in 1989, there was a long transition period where
package developers needed to worry about porting to older systems that did not support
ANSI C by default. These older systems are no longer in practical use and are no longer
supported by their original suppliers, so developers need not worry about this problem any
more.
Automake allows you to write packages that are portable to K&R C by de-ANSI-fying
each source file before the actual compilation takes place.
If the Makefile.am variable AUTOMAKE_OPTIONS (see Chapter 17 [Options], page 99)
contains the option ansi2knr then code to handle de-ANSI-fication is inserted into the
generated Makefile.in.
Chapter 8: Building Programs and Libraries 77
This causes each C source file in the directory to be treated as ANSI C. If an ANSI C
compiler is available, it is used. If no ANSI C compiler is available, the ansi2knr program
is used to convert the source files into K&R C, which is then compiled.
The ansi2knr program is simple-minded. It assumes the source code will be formatted
in a particular way; see the ansi2knr man page for details.
Support for the obsolete de-ANSI-fication feature requires the source files ansi2knr.c
and ansi2knr.1 to be in the same package as the ANSI C source; these files are distributed
with Automake. Also, the package configure.ac must call the macro AM_C_PROTOTYPES
(see Section 6.4 [Macros], page 42).
Automake also handles finding the ansi2knr support files in some other directory in the
current package. This is done by prepending the relative path to the appropriate directory
to the ansi2knr option. For instance, suppose the package has ANSI C code in the src
and lib subdirectories. The files ansi2knr.c and ansi2knr.1 appear in lib. Then this
could appear in src/Makefile.am:
AUTOMAKE_OPTIONS = ../lib/ansi2knr
If no directory prefix is given, the files are assumed to be in the current directory.
Note that automatic de-ANSI-fication will not work when the package is being built
for a different host architecture. That is because automake currently has no way to build
ansi2knr for the build machine.
Using LIBOBJS with source de-ANSI-fication used to require hand-crafted code in
configure to append ‘$U’ to basenames in LIBOBJS. This is no longer true today. Starting
with version 2.54, Autoconf takes care of rewriting LIBOBJS and LTLIBOBJS. (see Section
“AC_LIBOBJ vs. LIBOBJS” in The Autoconf Manual)
8.18 Automatic dependency tracking
As a developer it is often painful to continually update the Makefile.in whenever the
include-file dependencies change in a project. Automake supplies a way to automatically
track dependency changes (see Section 2.2.12 [Dependency Tracking], page 11).
Automake always uses complete dependencies for a compilation, including system head-
ers. Automake’s model is that dependency computation should be a side effect of the build.
To this end, dependencies are computed by running all compilations through a special
wrapper program called depcomp. depcomp understands how to coax many different C and
C++ compilers into generating dependency information in the format it requires. ‘automake
-a’ will install depcomp into your source tree for you. If depcomp can’t figure out how to
properly invoke your compiler, dependency tracking will simply be disabled for your build.
Experience with earlier versions of Automake (see Section 28.2 [Dependency Tracking
Evolution], page 143) taught us that it is not reliable to generate dependencies only on the
maintainer’s system, as configurations vary too much. So instead Automake implements
dependency tracking at build time.
Automatic dependency tracking can be suppressed by putting no-dependencies in the
variable AUTOMAKE_OPTIONS, or passing no-dependencies as an argument to AM_INIT_
AUTOMAKE (this should be the preferred way). Or, you can invoke automake with the -i
option. Dependency tracking is enabled by default.
Chapter 9: Other Derived Objects 78
The person building your package also can choose to disable dependency tracking by
configuring with --disable-dependency-tracking.
8.19 Support for executable extensions
On some platforms, such as Windows, executables are expected to have an extension such as
.exe. On these platforms, some compilers (GCC among them) will automatically generate
foo.exe when asked to generate foo.
Automake provides mostly-transparent support for this. Unfortunately mostly doesn’t
yet mean fully. Until the English dictionary is revised, you will have to assist Automake if
your package must support those platforms.
One thing you must be aware of is that, internally, Automake rewrites something like
this:
bin_PROGRAMS = liver
to this:
bin_PROGRAMS = liver$(EXEEXT)
The targets Automake generates are likewise given the ‘$(EXEEXT)’ extension.
The variables TESTS, XFAIL_TESTS (see Chapter 15 [Tests], page 97) are also rewritten
if it contains filenames that have been declared as programs in the same Makefile. (This
is mostly useful when some programs from check_PROGRAMS are listed in TESTS.)
However, Automake cannot apply this rewriting to configure substitutions. This means
that if you are conditionally building a program using such a substitution, then your
configure.ac must take care to add ‘$(EXEEXT)’ when constructing the output variable.
With Autoconf 2.13 and earlier, you must explicitly use AC_EXEEXT to get this sup-
port. With Autoconf 2.50, AC_EXEEXT is run automatically if you configure a compiler (say,
through AC_PROG_CC).
Sometimes maintainers like to write an explicit link rule for their program. Without
executable extension support, this is easy—you simply write a rule whose target is the
name of the program. However, when executable extension support is enabled, you must
instead add the ‘$(EXEEXT)’ suffix.
Unfortunately, due to the change in Autoconf 2.50, this means you must always add this
extension. However, this is a problem for maintainers who know their package will never
run on a platform that has executable extensions. For those maintainers, the no-exeext
option (see Chapter 17 [Options], page 99) will disable this feature. This works in a fairly
ugly way; if no-exeext is seen, then the presence of a rule for a target named foo in
Makefile.am will override an automake-generated rule for ‘foo$(EXEEXT)’. Without the
no-exeext option, this use will give a diagnostic.
9 Other Derived Objects
Automake can handle derived objects that are not C programs. Sometimes the support for
actually building such objects must be explicitly supplied, but Automake will still automat-
ically handle installation and distribution.
Chapter 9: Other Derived Objects 79
9.1 Executable Scripts
It is possible to define and install programs that are scripts. Such programs are listed using
the SCRIPTS primary name. When the script is distributed in its final, installable form, the
Makefile usually looks as follows:
# Install my_script in $(bindir) and distribute it.
dist_bin_SCRIPTS = my_script
Script are not distributed by default; as we have just seen, those that should be dis-
tributed can be specified using a dist_ prefix as with other primaries.
Scripts can be installed in bindir, sbindir, libexecdir, or pkgdatadir.
Scripts that need not being installed can be listed in noinst_SCRIPTS, and among them,
those which are needed only by ‘make check’ should go in check_SCRIPTS.
When a script needs to be built, the Makefile.am should include the appropriate
rules. For instance the automake program itself is a Perl script that is generated from
automake.in. Here is how this is handled:
bin_SCRIPTS = automake
CLEANFILES = $(bin_SCRIPTS)
EXTRA_DIST = automake.in
do_subst = sed -e ’s,[@]datadir[@],$(datadir),g’ \
-e ’s,[@]PERL[@],$(PERL),g’ \
-e ’s,[@]PACKAGE[@],$(PACKAGE),g’ \
-e ’s,[@]VERSION[@],$(VERSION),g’ \
...
automake: automake.in Makefile
$(do_subst) < $(srcdir)/automake.in > automake
chmod +x automake
Such scripts for which a build rule has been supplied need to be deleted explicitly using
CLEANFILES (see Chapter 13 [Clean], page 93), and their sources have to be distributed,
usually with EXTRA_DIST (see Chapter 14 [Dist], page 93).
Another common way to build scripts is to process them from configure with AC_
CONFIG_FILES. In this situation Automake knows which files should be cleaned and dis-
tributed, and what the rebuild rules should look like.
For instance if configure.ac contains
AC_CONFIG_FILES([src/my_script], [chmod +x src/my_script])
to build src/my_script from src/my_script.in, then an src/Makefile.am to install this
script in $(bindir) can be as simple as
bin_SCRIPTS = my_script
CLEANFILES = $(bin_SCRIPTS)
There is no need for EXTRA_DIST or any build rule: Automake infers them from AC_CONFIG_
FILES (see Section 6.1 [Requirements], page 28). CLEANFILES is still useful, because by
default Automake will clean targets of AC_CONFIG_FILES in distclean, not clean.
Although this looks simpler, building scripts this way has one drawback: directory vari-
ables such as $(datadir) are not fully expanded and may refer to other directory variables.
Chapter 9: Other Derived Objects 80
9.2 Header files
Header files that must be installed are specified by the HEADERS family of variables. Headers
can be installed in includedir, oldincludedir, pkgincludedir or any other directory you
may have defined (see Section 3.3 [Uniform], page 19). For instance,
include_HEADERS = foo.h bar/bar.h
will install the two files as $(includedir)/foo.h and $(includedir)/bar.h.
The nobase_ prefix is also supported,
nobase_include_HEADERS = foo.h bar/bar.h
will install the two files as $(includedir)/foo.h and $(includedir)/bar/bar.h (see
Section 7.3 [Alternative], page 49).
Usually, only header files that accompany installed libraries need to be installed. Headers
used by programs or convenience libraries are not installed. The noinst_HEADERS variable
can be used for such headers. However when the header actually belongs to one convenient
library or program, we recommend listing it in the program’s or library’s _SOURCES variable
(see Section 8.1.1 [Program Sources], page 51) instead of in noinst_HEADERS. This is
clearer for the Makefile.am reader. noinst_HEADERS would be the right variable to use in
a directory containing only headers and no associated library or program.
All header files must be listed somewhere; in a _SOURCES variable or in a _HEADERS
variable. Missing ones will not appear in the distribution.
For header files that are built and must not be distributed, use the nodist_ prefix
as in nodist_include_HEADERS or nodist_prog_SOURCES. If these generated headers are
needed during the build, you must also ensure they exist before they are used (see Section 9.4
[Sources], page 80).
9.3 Architecture-independent data files
Automake supports the installation of miscellaneous data files using the DATA family of
variables.
Such data can be installed in the directories datadir, sysconfdir, sharedstatedir,
localstatedir, or pkgdatadir.
By default, data files are not included in a distribution. Of course, you can use the
dist_ prefix to change this on a per-variable basis.
Here is how Automake declares its auxiliary data files:
dist_pkgdata_DATA = clean-kr.am clean.am ...
9.4 Built sources
Because Automake’s automatic dependency tracking works as a side-effect of compilation
(see Section 8.18 [Dependencies], page 77) there is a bootstrap issue: a target should not
be compiled before its dependencies are made, but these dependencies are unknown until
the target is first compiled.
Ordinarily this is not a problem, because dependencies are distributed sources: they
preexist and do not need to be built. Suppose that foo.c includes foo.h. When it first
compiles foo.o, make only knows that foo.o depends on foo.c. As a side-effect of this
Chapter 9: Other Derived Objects 81
compilation depcomp records the foo.h dependency so that following invocations of make
will honor it. In these conditions, it’s clear there is no problem: either foo.o doesn’t exist
and has to be built (regardless of the dependencies), or accurate dependencies exist and
they can be used to decide whether foo.o should be rebuilt.
It’s a different story if foo.h doesn’t exist by the first make run. For instance, there
might be a rule to build foo.h. This time file.o’s build will fail because the compiler
can’t find foo.h. make failed to trigger the rule to build foo.h first by lack of dependency
information.
The BUILT_SOURCES variable is a workaround for this problem. A source file listed in
BUILT_SOURCES is made on ‘make all’ or ‘make check’ (or even ‘make install’) before
other targets are processed. However, such a source file is not compiled unless explicitly
requested by mentioning it in some other _SOURCES variable.
So, to conclude our introductory example, we could use ‘BUILT_SOURCES = foo.h’ to
ensure foo.h gets built before any other target (including foo.o) during ‘make all’ or
‘make check’.
BUILT_SOURCES is actually a bit of a misnomer, as any file which must be created early
in the build process can be listed in this variable. Moreover, all built sources do not
necessarily have to be listed in BUILT_SOURCES. For instance, a generated .c file doesn’t
need to appear in BUILT_SOURCES (unless it is included by another source), because it’s a
known dependency of the associated object.
It might be important to emphasize that BUILT_SOURCES is honored only by ‘make all’,
‘make check’ and ‘make install’. This means you cannot build a specific target (e.g., ‘make
foo’) in a clean tree if it depends on a built source. However it will succeed if you have run
‘make all’ earlier, because accurate dependencies are already available.
The next section illustrates and discusses the handling of built sources on a toy example.
9.4.1 Built sources example
Suppose that foo.c includes bindir.h, which is installation-dependent and not distributed:
it needs to be built. Here bindir.h defines the preprocessor macro bindir to the value of
the make variable bindir (inherited from configure).
We suggest several implementations below. It’s not meant to be an exhaustive listing of
all ways to handle built sources, but it will give you a few ideas if you encounter this issue.
First try
This first implementation will illustrate the bootstrap issue mentioned in the previous sec-
tion (see Section 9.4 [Sources], page 80).
Here is a tentative Makefile.am.
# This won’t work.
bin_PROGRAMS = foo
foo_SOURCES = foo.c
nodist_foo_SOURCES = bindir.h
CLEANFILES = bindir.h
bindir.h: Makefile
echo ’#define bindir "$(bindir)"’ >$@
Chapter 9: Other Derived Objects 82
This setup doesn’t work, because Automake doesn’t know that foo.c includes bindir.h.
Remember, automatic dependency tracking works as a side-effect of compilation, so the
dependencies of foo.o will be known only after foo.o has been compiled (see Section 8.18
[Dependencies], page 77). The symptom is as follows.
% make
source=’foo.c’ object=’foo.o’ libtool=no \
depfile=’.deps/foo.Po’ tmpdepfile=’.deps/foo.TPo’ \
depmode=gcc /bin/sh ./depcomp \
gcc -I. -I. -g -O2 -c ‘test -f ’foo.c’ || echo ’./’‘foo.c
foo.c:2: bindir.h: No such file or directory
make: *** [foo.o] Error 1
In this example bindir.h is not distributed nor installed, and it is not even being built
on-time. One may wonder if the ‘nodist_foo_SOURCES = bindir.h’ line has any use at
all. This line simply states that bindir.h is a source of foo, so for instance, it should be
inspected while generating tags (see Section 18.1 [Tags], page 103). In other words, it does
not help our present problem, and the build would fail identically without it.
Using BUILT_SOURCES
A solution is to require bindir.h to be built before anything else. This is what BUILT_
SOURCES is meant for (see Section 9.4 [Sources], page 80).
bin_PROGRAMS = foo
foo_SOURCES = foo.c
nodist_foo_SOURCES = bindir.h
BUILT_SOURCES = bindir.h
CLEANFILES = bindir.h
bindir.h: Makefile
echo ’#define bindir "$(bindir)"’ >$@
See how bindir.h get built first:
% make
echo ’#define bindir "/usr/local/bin"’ >bindir.h
make all-am
make[1]: Entering directory ‘/home/adl/tmp’
source=’foo.c’ object=’foo.o’ libtool=no \
depfile=’.deps/foo.Po’ tmpdepfile=’.deps/foo.TPo’ \
depmode=gcc /bin/sh ./depcomp \
gcc -I. -I. -g -O2 -c ‘test -f ’foo.c’ || echo ’./’‘foo.c
gcc -g -O2 -o foo foo.o
make[1]: Leaving directory ‘/home/adl/tmp’
However, as said earlier, BUILT_SOURCES applies only to the all, check, and install
targets. It still fails if you try to run ‘make foo’ explicitly:
% make clean
test -z "bindir.h" || rm -f bindir.h
test -z "foo" || rm -f foo
rm -f *.o
% : > .deps/foo.Po # Suppress previously recorded dependencies
Chapter 9: Other Derived Objects 83
% make foo
source=’foo.c’ object=’foo.o’ libtool=no \
depfile=’.deps/foo.Po’ tmpdepfile=’.deps/foo.TPo’ \
depmode=gcc /bin/sh ./depcomp \
gcc -I. -I. -g -O2 -c ‘test -f ’foo.c’ || echo ’./’‘foo.c
foo.c:2: bindir.h: No such file or directory
make: *** [foo.o] Error 1
Recording dependencies manually
Usually people are happy enough with BUILT_SOURCES because they never build targets such
as ‘make foo’ before ‘make all’, as in the previous example. However if this matters to you,
you can avoid BUILT_SOURCES and record such dependencies explicitly in the Makefile.am.
bin_PROGRAMS = foo
foo_SOURCES = foo.c
nodist_foo_SOURCES = bindir.h
foo.$(OBJEXT): bindir.h
CLEANFILES = bindir.h
bindir.h: Makefile
echo ’#define bindir "$(bindir)"’ >$@
You don’t have to list all the dependencies of foo.o explicitly, only those that might
need to be built. If a dependency already exists, it will not hinder the first compilation
and will be recorded by the normal dependency tracking code. (Note that after this first
compilation the dependency tracking code will also have recorded the dependency between
foo.o and bindir.h; so our explicit dependency is really useful to the first build only.)
Adding explicit dependencies like this can be a bit dangerous if you are not careful
enough. This is due to the way Automake tries not to overwrite your rules (it assumes you
know better than it). ‘foo.$(OBJEXT): bindir.h’ supersedes any rule Automake may want
to output to build ‘foo.$(OBJEXT)’. It happens to work in this case because Automake
doesn’t have to output any ‘foo.$(OBJEXT):’ target: it relies on a suffix rule instead (i.e.,
‘.c.$(OBJEXT):’). Always check the generated Makefile.in if you do this.
Build bindir.h from configure
It’s possible to define this preprocessor macro from configure, either in config.h (see
Section “Defining Directories” in The Autoconf Manual), or by processing a bindir.h.in
file using AC_CONFIG_FILES (see Section “Configuration Actions” in The Autoconf Manual).
At this point it should be clear that building bindir.h from configure work well for
this example. bindir.h will exist before you build any target, hence will not cause any
dependency issue.
The Makefile can be shrunk as follows. We do not even have to mention bindir.h.
bin_PROGRAMS = foo
foo_SOURCES = foo.c
However, it’s not always possible to build sources from configure, especially when these
sources are generated by a tool that needs to be built first...
Chapter 10: Other GNU Tools 84
Build bindir.c, not bindir.h.
Another attractive idea is to define bindir as a variable or function exported from bindir.o,
and build bindir.c instead of bindir.h.
noinst_PROGRAMS = foo
foo_SOURCES = foo.c bindir.h
nodist_foo_SOURCES = bindir.c
CLEANFILES = bindir.c
bindir.c: Makefile
echo ’const char bindir[] = "$(bindir)";’ >$@
bindir.h contains just the variable’s declaration and doesn’t need to be built, so it
won’t cause any trouble. bindir.o is always dependent on bindir.c, so bindir.c will get
built first.
Which is best?
There is no panacea, of course. Each solution has its merits and drawbacks.
You cannot use BUILT_SOURCES if the ability to run ‘make foo’ on a clean tree is impor-
tant to you.
You won’t add explicit dependencies if you are leery of overriding an Automake rule by
mistake.
Building files from ./configure is not always possible, neither is converting .h files into
.c files.
10 Other GNU Tools
Since Automake is primarily intended to generate Makefile.ins for use in GNU programs,
it tries hard to interoperate with other GNU tools.
10.1 Emacs Lisp
Automake provides some support for Emacs Lisp. The LISP primary is used to hold a list
of .el files. Possible prefixes for this primary are lisp_ and noinst_. Note that if lisp_
LISP is defined, then configure.ac must run AM_PATH_LISPDIR (see Section 6.4 [Macros],
page 42).
Lisp sources are not distributed by default. You can prefix the LISP primary with
dist_, as in dist_lisp_LISP or dist_noinst_LISP, to indicate that these files should be
distributed.
Automake will byte-compile all Emacs Lisp source files using the Emacs found by AM_
PATH_LISPDIR, if any was found.
Byte-compiled Emacs Lisp files are not portable among all versions of Emacs, so it
makes sense to turn this off if you expect sites to have more than one version of Emacs
installed. Furthermore, many packages don’t actually benefit from byte-compilation. Still,
we recommend that you byte-compile your Emacs Lisp sources. It is probably better for
sites with strange setups to cope for themselves than to make the installation less nice for
everybody else.
Chapter 10: Other GNU Tools 85
There are two ways to avoid byte-compiling. Historically, we have recommended the
following construct.
lisp_LISP = file1.el file2.el
ELCFILES =
ELCFILES is an internal Automake variable that normally lists all .elc files that must be
byte-compiled. Automake defines ELCFILES automatically from lisp_LISP. Emptying this
variable explicitly prevents byte-compilation to occur.
Since Automake 1.8, we now recommend using lisp_DATA instead. As in
lisp_DATA = file1.el file2.el
Note that these two constructs are not equivalent. _LISP will not install a file if Emacs
is not installed, while _DATA will always install its files.
10.2 Gettext
If AM_GNU_GETTEXT is seen in configure.ac, then Automake turns on support for GNU
gettext, a message catalog system for internationalization (see Section “Introduction” in
GNU gettext utilities).
The gettext support in Automake requires the addition of one or two subdirectories
to the package, po and possibly also intl. The latter is needed if AM_GNU_GETTEXT is
not invoked with the ‘external’ argument, or if AM_GNU_GETTEXT_INTL_SUBDIR is used.
Automake ensures that these directories exist and are mentioned in SUBDIRS.
10.3 Libtool
Automake provides support for GNU Libtool (see Section “Introduction” in The Libtool
Manual) with the LTLIBRARIES primary. See Section 8.3 [A Shared Library], page 55.
10.4 Java
Automake provides some minimal support for Java compilation with the JAVA primary.
Any .java files listed in a _JAVA variable will be compiled with JAVAC at build time. By
default, .java files are not included in the distribution, you should use the dist_ prefix to
distribute them.
Here is a typical setup for distributing .java files and installing the .class files resulting
from their compilation.
javadir = $(datadir)/java
dist_java_JAVA = a.java b.java ...
Currently Automake enforces the restriction that only one _JAVA primary can be used in
a given Makefile.am. The reason for this restriction is that, in general, it isn’t possible to
know which .class files were generated from which .java files, so it would be impossible
to know which files to install where. For instance, a .java file can define multiple classes;
the resulting .class file names cannot be predicted without parsing the .java file.
There are a few variables that are used when compiling Java sources:
JAVAC The name of the Java compiler. This defaults to ‘javac’.
Chapter 10: Other GNU Tools 86
JAVACFLAGS
The flags to pass to the compiler. This is considered to be a user variable (see
Section 3.5 [User Variables], page 21).
AM_JAVACFLAGS
More flags to pass to the Java compiler. This, and not JAVACFLAGS, should be
used when it is necessary to put Java compiler flags into Makefile.am.
JAVAROOT The value of this variable is passed to the -d option to javac. It defaults to
‘$(top_builddir)’.
CLASSPATH_ENV
This variable is an sh expression that is used to set the CLASSPATH environment
variable on the javac command line. (In the future we will probably handle
class path setting differently.)
10.5 Python
Automake provides support for Python compilation with the PYTHON primary. A typi-
cal setup is to call AM_PATH_PYTHON in configure.ac and use a line like the following in
Makefile.am:
python_PYTHON = tree.py leave.py
Any files listed in a _PYTHON variable will be byte-compiled with py-compile at in-
stall time. py-compile actually creates both standard (.pyc) and optimized (.pyo) byte-
compiled versions of the source files. Note that because byte-compilation occurs at install
time, any files listed in noinst_PYTHON will not be compiled. Python source files are in-
cluded in the distribution by default, prepend nodist_ (as in nodist_python_PYTHON) to
omit them.
Automake ships with an Autoconf macro called AM_PATH_PYTHON that will determine
some Python-related directory variables (see below). If you have called AM_PATH_PYTHON
from configure.ac, then you may use the variables python_PYTHON or pkgpython_PYTHON
to list Python source files in your Makefile.am, depending where you want your files in-
stalled (see the definitions of pythondir and pkgpythondir below).
AM_PATH_PYTHON ([VERSION], [ACTION-IF-FOUND], [Macro]
[ACTION-IF-NOT-FOUND])
Search for a Python interpreter on the system. This macro takes three optional
arguments. The first argument, if present, is the minimum version of Python required
for this package: AM_PATH_PYTHON will skip any Python interpreter that is older than
VERSION. If an interpreter is found and satisfies VERSION, then ACTION-IF-
FOUND is run. Otherwise, ACTION-IF-NOT-FOUND is run.
If ACTION-IF-NOT-FOUND is not specified, as in the following example, the default
is to abort configure.
AM_PATH_PYTHON([2.2])
This is fine when Python is an absolute requirement for the package. If Python >=
2.2 was only optional to the package, AM_PATH_PYTHON could be called as follows.
AM_PATH_PYTHON([2.2],, [:])
Chapter 10: Other GNU Tools 87
AM_PATH_PYTHON creates the following output variables based on the Python instal-
lation found during configuration.
PYTHON The name of the Python executable, or ‘:’ if no suitable interpreter could be
found.
Assuming ACTION-IF-NOT-FOUND is used (otherwise ./configure will
abort if Python is absent), the value of PYTHON can be used to setup a
conditional in order to disable the relevant part of a build as follows.
AM_PATH_PYTHON(,, [:])
AM_CONDITIONAL([HAVE_PYTHON], [test "$PYTHON" != :])
PYTHON_VERSION
The Python version number, in the form major.minor (e.g., ‘1.5’). This is
currently the value of ‘sys.version[:3]’.
PYTHON_PREFIX
The string ‘${prefix}’. This term may be used in future work that needs the
contents of Python’s ‘sys.prefix’, but general consensus is to always use the
value from configure.
PYTHON_EXEC_PREFIX
The string ‘${exec_prefix}’. This term may be used in future work that needs
the contents of Python’s ‘sys.exec_prefix’, but general consensus is to always
use the value from configure.
PYTHON_PLATFORM
The canonical name used by Python to describe the operating system, as given
by ‘sys.platform’. This value is sometimes needed when building Python
extensions.
pythondir
The directory name for the site-packages subdirectory of the standard Python
install tree.
pkgpythondir
This is the directory under pythondir that is named after the package. That
is, it is ‘$(pythondir)/$(PACKAGE)’. It is provided as a convenience.
pyexecdir
This is the directory where Python extension modules (shared libraries) should
be installed. An extension module written in C could be declared as follows to
Automake:
pyexec_LTLIBRARIES = quaternion.la
quaternion_SOURCES = quaternion.c support.c support.h
quaternion_la_LDFLAGS = -avoid-version -module
pkgpyexecdir
This is a convenience variable that is defined as ‘$(pyexecdir)/$(PACKAGE)’.
All these directory variables have values that start with either ‘${prefix}’ or
‘${exec_prefix}’ unexpanded. This works fine in Makefiles, but it makes these variables
hard to use in configure. This is mandated by the GNU coding standards, so that the
Chapter 11: Building documentation 88
user can run ‘make prefix=/foo install’. The Autoconf manual has a section with
more details on this topic (see Section “Installation Directory Variables” in The Autoconf
Manual). See also Section 27.10 [Hard-Coded Install Paths], page 129.
11 Building documentation
Currently Automake provides support for Texinfo and man pages.
11.1 Texinfo
If the current directory contains Texinfo source, you must declare it with the TEXINFOS
primary. Generally Texinfo files are converted into info, and thus the info_TEXINFOS
variable is most commonly used here. Any Texinfo source file must end in the .texi, .txi,
or .texinfo extension. We recommend .texi for new manuals.
Automake generates rules to build .info, .dvi, .ps, .pdf and .html files from your
Texinfo sources. Following the GNU Coding Standards, only the .info files are built by
‘make all’ and installed by ‘make install’ (unless you use no-installinfo, see below).
Furthermore, .info files are automatically distributed so that Texinfo is not a prerequisite
for installing your package.
Other documentation formats can be built on request by ‘make dvi’, ‘make ps’,
‘make pdf’ and ‘make html’, and they can be installed with ‘make install-dvi’, ‘make
install-ps’, ‘make install-pdf’ and ‘make install-html’ explicitly. ‘make uninstall’
will remove everything: the Texinfo documentation installed by default as well as all the
above optional formats.
All these targets can be extended using ‘-local’ rules (see Section 23.1 [Extending],
page 108).
If the .texi file @includes version.texi, then that file will be automatically generated.
The file version.texi defines four Texinfo flag you can reference using @value{EDITION},
@value{VERSION}, @value{UPDATED}, and @value{UPDATED-MONTH}.
EDITION
VERSION Both of these flags hold the version number of your program. They are kept
separate for clarity.
UPDATED This holds the date the primary .texi file was last modified.
UPDATED-MONTH
This holds the name of the month in which the primary .texi file was last
modified.
The version.texi support requires the mdate-sh script; this script is supplied with
Automake and automatically included when automake is invoked with the --add-missing
option.
If you have multiple Texinfo files, and you want to use the version.texi feature, then
you have to have a separate version file for each Texinfo file. Automake will treat any include
in a Texinfo file that matches vers*.texi just as an automatically generated version file.
Chapter 11: Building documentation 89
Sometimes an info file actually depends on more than one .texi file. For instance, in
GNU Hello, hello.texi includes the file gpl.texi. You can tell Automake about these
dependencies using the texi_TEXINFOS variable. Here is how GNU Hello does it:
info_TEXINFOS = hello.texi
hello_TEXINFOS = gpl.texi
By default, Automake requires the file texinfo.tex to appear in the same directory
as the Makefile.am file that lists the .texi files. If you used AC_CONFIG_AUX_DIR in
configure.ac (see Section “Finding ‘configure’ Input” in The Autoconf Manual), then
texinfo.tex is looked for there. In both cases, automake then supplies texinfo.tex if
--add-missing is given, and takes care of its distribution. However, if you set the TEXINFO_
TEX variable (see below), it overrides the location of the file and turns off its installation
into the source as well as its distribution.
The option no-texinfo.tex can be used to eliminate the requirement for the file
texinfo.tex. Use of the variable TEXINFO_TEX is preferable, however, because that allows
the dvi, ps, and pdf targets to still work.
Automake generates an install-info rule; some people apparently use this. By default,
info pages are installed by ‘make install’, so running make install-info is pointless. This
can be prevented via the no-installinfo option. In this case, .info files are not installed
by default, and user must request this explicitly using ‘make install-info’
The following variables are used by the Texinfo build rules.
MAKEINFO The name of the program invoked to build .info files. This variable is defined
by Automake. If the makeinfo program is found on the system then it will be
used by default; otherwise missing will be used instead.
MAKEINFOHTML
The command invoked to build .html files. Automake defines this to
‘$(MAKEINFO) --html’.
MAKEINFOFLAGS
User flags passed to each invocation of ‘$(MAKEINFO)’ and ‘$(MAKEINFOHTML)’.
This user variable (see Section 3.5 [User Variables], page 21) is not expected to
be defined in any Makefile; it can be used by users to pass extra flags to suit
their needs.
AM_MAKEINFOFLAGS
AM_MAKEINFOHTMLFLAGS
Maintainer flags passed to each makeinfo invocation. Unlike MAKEINFOFLAGS,
these variables are meant to be defined by maintainers in Makefile.am.
‘$(AM_MAKEINFOFLAGS)’ is passed to makeinfo when building .info files; and
‘$(AM_MAKEINFOHTMLFLAGS)’ is used when building .html files.
For instance, the following setting can be used to obtain one single .html file
per manual, without node separators.
AM_MAKEINFOHTMLFLAGS = --no-headers --no-split
AM_MAKEINFOHTMLFLAGS defaults to ‘$(AM_MAKEINFOFLAGS)’. This means that
defining AM_MAKEINFOFLAGS without defining AM_MAKEINFOHTMLFLAGS will im-
pact builds of both .info and .html files.
Chapter 11: Building documentation 90
TEXI2DVI The name of the command that converts a .texi file into a .dvi file. This
defaults to ‘texi2dvi’, a script that ships with the Texinfo package.
TEXI2PDF The name of the command that translates a .texi file into a .pdf file. This
defaults to ‘$(TEXI2DVI) --pdf --batch’.
DVIPS The name of the command that build a .ps file out of a .dvi file. This defaults
to ‘dvips’.
TEXINFO_TEX
If your package has Texinfo files in many directories, you can use the variable
TEXINFO_TEX to tell Automake where to find the canonical texinfo.tex for
your package. The value of this variable should be the relative path from the
current Makefile.am to texinfo.tex:
TEXINFO_TEX = ../doc/texinfo.tex
11.2 Man pages
A package can also include man pages (but see the GNU standards on this matter, Section
“Man Pages” in The GNU Coding Standards.) Man pages are declared using the MANS
primary. Generally the man_MANS variable is used. Man pages are automatically installed
in the correct subdirectory of mandir, based on the file extension.
File extensions such as .1c are handled by looking for the valid part of the extension
and using that to determine the correct subdirectory of mandir. Valid section names are
the digits ‘0’ through ‘9’, and the letters ‘l’ and ‘n’.
Sometimes developers prefer to name a man page something like foo.man in the source,
and then rename it to have the correct suffix, for example foo.1, when installing the
file. Automake also supports this mode. For a valid section named SECTION, there is a
corresponding directory named ‘manSECTIONdir’, and a corresponding _MANS variable. Files
listed in such a variable are installed in the indicated section. If the file already has a valid
suffix, then it is installed as-is; otherwise the file suffix is changed to match the section.
For instance, consider this example:
man1_MANS = rename.man thesame.1 alsothesame.1c
In this case, rename.man will be renamed to rename.1 when installed, but the other files
will keep their names.
By default, man pages are installed by ‘make install’. However, since the GNU project
does not require man pages, many maintainers do not expend effort to keep the man pages
up to date. In these cases, the no-installman option will prevent the man pages from being
installed by default. The user can still explicitly install them via ‘make install-man’.
Man pages are not currently considered to be source, because it is not uncommon for
man pages to be automatically generated. Therefore they are not automatically included
in the distribution. However, this can be changed by use of the dist_ prefix. For instance
here is how to distribute and install the two man pages of GNU cpio (which includes both
Texinfo documentation and man pages):
dist_man_MANS = cpio.1 mt.1
The nobase_ prefix is meaningless for man pages and is disallowed.
Chapter 12: What Gets Installed 91
Executables and manpages may be renamed upon installation (see Section 2.2.9 [Re-
naming], page 10). For manpages this can be avoided by use of the notrans_ prefix. For
instance, suppose an executable ‘foo’ allowing to access a library function ‘foo’ from the
command line. The way to avoid renaming of the foo.3 manpage is:
man_MANS = foo.1
notrans_man_MANS = foo.3
‘notrans_’ must be specified first when used in conjunction with either ‘dist_’ or
‘nodist_’ (see Chapter 14 [Dist], page 93). For instance:
notrans_dist_man3_MANS = bar.3
12 What Gets Installed
12.1 Basics of installation
Naturally, Automake handles the details of actually installing your program once it has been
built. All files named by the various primaries are automatically installed in the appropriate
places when the user runs ‘make install’.
A file named in a primary is installed by copying the built file into the appropriate
directory. The base name of the file is used when installing.
bin_PROGRAMS = hello subdir/goodbye
In this example, both ‘hello’ and ‘goodbye’ will be installed in ‘$(bindir)’.
Sometimes it is useful to avoid the basename step at install time. For instance, you
might have a number of header files in subdirectories of the source tree that are laid out
precisely how you want to install them. In this situation you can use the nobase_ prefix to
suppress the base name step. For example:
nobase_include_HEADERS = stdio.h sys/types.h
Will install stdio.h in ‘$(includedir)’ and types.h in ‘$(includedir)/sys’.
12.2 The two parts of install
Automake generates separate install-data and install-exec rules, in case the installer
is installing on multiple machines that share directory structure—these targets allow the
machine-independent parts to be installed only once. install-exec installs platform-
dependent files, and install-data installs platform-independent files. The install target
depends on both of these targets. While Automake tries to automatically segregate objects
into the correct category, the Makefile.am author is, in the end, responsible for making
sure this is done correctly.
Variables using the standard directory prefixes ‘data’, ‘info’, ‘man’, ‘include’,
‘oldinclude’, ‘pkgdata’, or ‘pkginclude’ are installed by install-data.
Variables using the standard directory prefixes ‘bin’, ‘sbin’, ‘libexec’, ‘sysconf’,
‘localstate’, ‘lib’, or ‘pkglib’ are installed by install-exec.
For instance, data_DATA files are installed by install-data, while bin_PROGRAMS files
are installed by install-exec.
Chapter 12: What Gets Installed 92
Any variable using a user-defined directory prefix with ‘exec’ in the name (e.g.,
myexecbin_PROGRAMS) is installed by install-exec. All other user-defined prefixes are
installed by install-data.
12.3 Extending installation
It is possible to extend this mechanism by defining an install-exec-local or
install-data-local rule. If these rules exist, they will be run at ‘make install’ time.
These rules can do almost anything; care is required.
Automake also supports two install hooks, install-exec-hook and install-data-
hook. These hooks are run after all other install rules of the appropriate type, exec or data,
have completed. So, for instance, it is possible to perform post-installation modifications
using an install hook. See Section 23.1 [Extending], page 108, for some examples.
12.4 Staged installs
Automake generates support for the DESTDIR variable in all install rules. DESTDIR is used
during the ‘make install’ step to relocate install objects into a staging area. Each object
and path is prefixed with the value of DESTDIR before being copied into the install area.
Here is an example of typical DESTDIR usage:
mkdir /tmp/staging &&
make DESTDIR=/tmp/staging install
The mkdir command avoids a security problem if the attacker creates a symbolic
link from /tmp/staging to a victim area; then make places install objects in a directory
tree built under /tmp/staging. If /gnu/bin/foo and /gnu/share/aclocal/foo.m4
are to be installed, the above command would install /tmp/staging/gnu/bin/foo and
/tmp/staging/gnu/share/aclocal/foo.m4.
This feature is commonly used to build install images and packages (see Section 2.2.10
[DESTDIR], page 10).
Support for DESTDIR is implemented by coding it directly into the install rules. If your
Makefile.am uses a local install rule (e.g., install-exec-local) or an install hook, then
you must write that code to respect DESTDIR.
See Section “Makefile Conventions” in The GNU Coding Standards, for another usage
example.
12.5 Rules for the user
Automake also generates rules for targets uninstall, installdirs, and install-strip.
Automake supports uninstall-local and uninstall-hook. There is no notion of sep-
arate uninstalls for “exec” and “data”, as these features would not provide additional func-
tionality.
Note that uninstall is not meant as a replacement for a real packaging tool.
Chapter 14: What Goes in a Distribution 93
13 What Gets Cleaned
The GNU Makefile Standards specify a number of different clean rules. See Section “Stan-
dard Targets for Users” in The GNU Coding Standards.
Generally the files that can be cleaned are determined automatically by Automake. Of
course, Automake also recognizes some variables that can be defined to specify additional
files to clean. These variables are MOSTLYCLEANFILES, CLEANFILES, DISTCLEANFILES, and
MAINTAINERCLEANFILES.
When cleaning involves more than deleting some hard-coded list of files, it is also possible
to supplement the cleaning rules with your own commands. Simply define a rule for any of
the mostlyclean-local, clean-local, distclean-local, or maintainer-clean-local
targets (see Section 23.1 [Extending], page 108). A common case is deleting a directory, for
instance, a directory created by the test suite:
clean-local:
-rm -rf testSubDir
As the GNU Standards aren’t always explicit as to which files should be removed by
which rule, we’ve adopted a heuristic that we believe was first formulated by François
Pinard:
• If make built it, and it is commonly something that one would want to rebuild (for
instance, a .o file), then mostlyclean should delete it.
• Otherwise, if make built it, then clean should delete it.
• If configure built it, then distclean should delete it.
• If the maintainer built it (for instance, a .info file), then maintainer-clean should
delete it. However maintainer-clean should not delete anything that needs to exist
in order to run ‘./configure && make’.
We recommend that you follow this same set of heuristics in your Makefile.am.
14 What Goes in a Distribution
14.1 Basics of distribution
The dist rule in the generated Makefile.in can be used to generate a gzipped tar file
and other flavors of archive for distribution. The files is named based on the PACKAGE and
VERSION variables defined by AM_INIT_AUTOMAKE (see Section 6.4 [Macros], page 42); more
precisely the gzipped tar file is named ‘package-version.tar.gz’. You can use the make
variable GZIP_ENV to control how gzip is run. The default setting is --best.
For the most part, the files to distribute are automatically found by Automake: all source
files are automatically included in a distribution, as are all Makefile.ams and Makefile.ins.
Automake also has a built-in list of commonly used files that are automatically included if
they are found in the current directory (either physically, or as the target of a Makefile.am
rule). This list is printed by ‘automake --help’. Also, files that are read by configure (i.e.
the source files corresponding to the files specified in various Autoconf macros such as AC_
CONFIG_FILES and siblings) are automatically distributed. Files included in Makefile.ams
Chapter 14: What Goes in a Distribution 94
(using include) or in configure.ac (using m4_include), and helper scripts installed with
‘automake --add-missing’ are also distributed.
Still, sometimes there are files that must be distributed, but which are not covered in the
automatic rules. These files should be listed in the EXTRA_DIST variable. You can mention
files from subdirectories in EXTRA_DIST.
You can also mention a directory in EXTRA_DIST; in this case the entire directory will be
recursively copied into the distribution. Please note that this will also copy everything in
the directory, including CVS/RCS version control files. We recommend against using this
feature.
If you define SUBDIRS, Automake will recursively include the subdirectories in the dis-
tribution. If SUBDIRS is defined conditionally (see Chapter 20 [Conditionals], page 105),
Automake will normally include all directories that could possibly appear in SUBDIRS in
the distribution. If you need to specify the set of directories conditionally, you can set the
variable DIST_SUBDIRS to the exact list of subdirectories to include in the distribution (see
Section 7.2 [Conditional Subdirectories], page 46).
14.2 Fine-grained distribution control
Sometimes you need tighter control over what does not go into the distribution; for instance,
you might have source files that are generated and that you do not want to distribute. In
this case Automake gives fine-grained control using the dist and nodist prefixes. Any
primary or _SOURCES variable can be prefixed with dist_ to add the listed files to the
distribution. Similarly, nodist_ can be used to omit the files from the distribution.
As an example, here is how you would cause some data to be distributed while leaving
some source code out of the distribution:
dist_data_DATA = distribute-this
bin_PROGRAMS = foo
nodist_foo_SOURCES = do-not-distribute.c
14.3 The dist hook
Occasionally it is useful to be able to change the distribution before it is packaged up. If the
dist-hook rule exists, it is run after the distribution directory is filled, but before the actual
tar (or shar) file is created. One way to use this is for distributing files in subdirectories for
which a new Makefile.am is overkill:
dist-hook:
mkdir $(distdir)/random
cp -p $(srcdir)/random/a1 $(srcdir)/random/a2 $(distdir)/random
Another way to use this is for removing unnecessary files that get recursively included
by specifying a directory in EXTRA DIST:
EXTRA_DIST = doc
dist-hook:
rm -rf ‘find $(distdir)/doc -name CVS‘
Two variables that come handy when writing dist-hook rules are ‘$(distdir)’ and
‘$(top_distdir)’.
Chapter 14: What Goes in a Distribution 95
‘$(distdir)’ points to the directory where the dist rule will copy files from the current
directory before creating the tarball. If you are at the top-level directory, then ‘distdir
= $(PACKAGE)-$(VERSION)’. When used from subdirectory named foo/, then ‘distdir =
../$(PACKAGE)-$(VERSION)/foo’. ‘$(distdir)’ can be a relative or absolute path, do not
assume any form.
‘$(top_distdir)’ always points to the root directory of the distributed tree. At
the top-level it’s equal to ‘$(distdir)’. In the foo/ subdirectory ‘top_distdir =
../$(PACKAGE)-$(VERSION)’. ‘$(top_distdir)’ too can be a relative or absolute path.
Note that when packages are nested using AC_CONFIG_SUBDIRS (see Section 7.4 [Sub-
packages], page 49), then ‘$(distdir)’ and ‘$(top_distdir)’ are relative to the package
where ‘make dist’ was run, not to any sub-packages involved.
14.4 Checking the distribution
Automake also generates a distcheck rule that can be of help to ensure that a given
distribution will actually work. distcheck makes a distribution, then tries to do a VPATH
build (see Section 2.2.6 [VPATH Builds], page 6), run the test suite, and finally make
another tarball to ensure the distribution is self-contained.
Building the package involves running ‘./configure’. If you need to supply additional
flags to configure, define them in the DISTCHECK_CONFIGURE_FLAGS variable, either in
your top-level Makefile.am, or on the command line when invoking make.
If the distcheck-hook rule is defined in your top-level Makefile.am, then it will be
invoked by distcheck after the new distribution has been unpacked, but before the un-
packed copy is configured and built. Your distcheck-hook can do almost anything, though
as always caution is advised. Generally this hook is used to check for potential distribu-
tion errors not caught by the standard mechanism. Note that distcheck-hook as well
as DISTCHECK_CONFIGURE_FLAGS are not honored in a subpackage Makefile.am, but the
DISTCHECK_CONFIGURE_FLAGS are passed down to the configure script of the subpackage.
Speaking of potential distribution errors, distcheck also ensures that the distclean
rule actually removes all built files. This is done by running ‘make distcleancheck’ at the
end of the VPATH build. By default, distcleancheck will run distclean and then make
sure the build tree has been emptied by running ‘$(distcleancheck_listfiles)’. Usually
this check will find generated files that you forgot to add to the DISTCLEANFILES variable
(see Chapter 13 [Clean], page 93).
The distcleancheck behavior should be OK for most packages, otherwise you have
the possibility to override the definition of either the distcleancheck rule, or the
‘$(distcleancheck_listfiles)’ variable. For instance, to disable distcleancheck
completely, add the following rule to your top-level Makefile.am:
distcleancheck:
@:
If you want distcleancheck to ignore built files that have not been cleaned because
they are also part of the distribution, add the following definition instead:
distcleancheck_listfiles = \
find -type f -exec sh -c ’test -f $(srcdir)/{} || echo {}’ ’;’
Chapter 14: What Goes in a Distribution 96
The above definition is not the default because it’s usually an error if your Makefiles
cause some distributed files to be rebuilt when the user build the package. (Think about
the user missing the tool required to build the file; or if the required tool is built by your
package, consider the cross-compilation case where it can’t be run.) There is a FAQ entry
about this (see Section 27.5 [distcleancheck], page 120), make sure you read it before playing
with distcleancheck_listfiles.
distcheck also checks that the uninstall rule works properly, both for ordinary and
DESTDIR builds. It does this by invoking ‘make uninstall’, and then it checks the install
tree to see if any files are left over. This check will make sure that you correctly coded your
uninstall-related rules.
By default, the checking is done by the distuninstallcheck rule, and the list of files
in the install tree is generated by ‘$(distuninstallcheck_listfiles’) (this is a variable
whose value is a shell command to run that prints the list of files to stdout).
Either of these can be overridden to modify the behavior of distcheck. For instance,
to disable this check completely, you would write:
distuninstallcheck:
@:
14.5 The types of distributions
Automake generates rules to provide archives of the project for distributions in various
formats. Their targets are:
dist-bzip2
Generate a bzip2 tar archive of the distribution. bzip2 archives are frequently
smaller than gzipped archives.
dist-gzip
Generate a gzip tar archive of the distribution.
dist-lzma
Generate a lzma tar archive of the distribution. lzma archives are frequently
smaller than bzip2-compressed archives.
dist-shar
Generate a shar archive of the distribution.
dist-zip Generate a zip archive of the distribution.
dist-tarZ
Generate a compressed tar archive of the distribution.
The rule dist (and its historical synonym dist-all) will create archives in all the
enabled formats, Chapter 17 [Options], page 99. By default, only the dist-gzip target is
hooked to dist.
Chapter 15: Support for test suites 97
15 Support for test suites
Automake supports two forms of test suites.
15.1 Simple Tests
If the variable TESTS is defined, its value is taken to be a list of programs or scripts to run
in order to do the testing. Programs needing data files should look for them in srcdir
(which is both an environment variable and a make variable) so they work when building
in a separate directory (see Section “Build Directories ” in The Autoconf Manual), and in
particular for the distcheck rule (see Chapter 14 [Dist], page 93).
For each of the TESTS, the result of execution is printed along with the test name, where
PASS denotes a successful test, FAIL denotes a failed test, XFAIL an expected failure, XPASS
an unexpected pass for a test that is supposed to fail, and SKIP denotes a skipped test.
The number of failures will be printed at the end of the run. If a given test program
exits with a status of 77, then its result is ignored in the final count. This feature allows
non-portable tests to be ignored in environments where they don’t make sense.
If the Automake option color-tests is used (see Chapter 17 [Options], page 99) and
standard output is connected to a capable terminal, then the test results and the summary
are colored appropriately. The user can disable colored output by setting the make variable
‘AM_COLOR_TESTS=no’, or force colored output even without a connecting terminal with
‘AM_COLOR_TESTS=always’.
The variable TESTS_ENVIRONMENT can be used to set environment variables for the test
run; the environment variable srcdir is set in the rule. If all your test programs are scripts,
you can also set TESTS_ENVIRONMENT to an invocation of the shell (e.g. ‘$(SHELL) -x’ can
be useful for debugging the tests), or any other interpreter. For instance the following setup
is used by the Automake package to run four tests in Perl.
TESTS_ENVIRONMENT = $(PERL) -Mstrict -I $(top_srcdir)/lib -w
TESTS = Condition.pl DisjConditions.pl Version.pl Wrap.pl
You may define the variable XFAIL_TESTS to a list of tests (usually a subset of TESTS)
that are expected to fail. This will reverse the result of those tests.
Automake ensures that each file listed in TESTS is built before any tests are run; you can
list both source and derived programs (or scripts) in TESTS; the generated rule will look
both in srcdir and .. For instance, you might want to run a C program as a test. To do
this you would list its name in TESTS and also in check_PROGRAMS, and then specify it as
you would any other program.
Programs listed in check_PROGRAMS (and check_LIBRARIES, check_LTLIBRARIES...) are
only built during make check, not during make all. You should list there any program
needed by your tests that does not need to be built by make all. Note that check_PROGRAMS
are not automatically added to TESTS because check_PROGRAMS usually lists programs used
by the tests, not the tests themselves. Of course you can set TESTS = $(check_PROGRAMS)
if all your programs are test cases.
Chapter 16: Rebuilding Makefiles 98
15.2 DejaGnu Tests
If dejagnu (ftp://ftp.gnu.org/gnu/dejagnu/) appears in AUTOMAKE_OPTIONS, then a
dejagnu-based test suite is assumed. The variable DEJATOOL is a list of names that are
passed, one at a time, as the --tool argument to runtest invocations; it defaults to the
name of the package.
The variable RUNTESTDEFAULTFLAGS holds the --tool and --srcdir flags that are passed
to dejagnu by default; this can be overridden if necessary.
The variables EXPECT and RUNTEST can also be overridden to provide project-specific
values. For instance, you will need to do this if you are testing a compiler toolchain,
because the default values do not take into account host and target names.
The contents of the variable RUNTESTFLAGS are passed to the runtest invocation. This
is considered a “user variable” (see Section 3.5 [User Variables], page 21). If you need to
set runtest flags in Makefile.am, you can use AM_RUNTESTFLAGS instead.
Automake will generate rules to create a local site.exp file, defining various variables
detected by configure. This file is automatically read by DejaGnu. It is OK for the user
of a package to edit this file in order to tune the test suite. However this is not the place
where the test suite author should define new variables: this should be done elsewhere in
the real test suite code. Especially, site.exp should not be distributed.
For more information regarding DejaGnu test suites, see The DejaGnu Manual.
In either case, the testing is done via ‘make check’.
15.3 Install Tests
The installcheck target is available to the user as a way to run any tests after the package
has been installed. You can add tests to this by writing an installcheck-local rule.
16 Rebuilding Makefiles
Automake generates rules to automatically rebuild Makefiles, configure, and other de-
rived files like Makefile.in.
If you are using AM_MAINTAINER_MODE in configure.ac, then these automatic rebuilding
rules are only enabled in maintainer mode.
Sometimes you need to run aclocal with an argument like -I to tell it where to find
.m4 files. Since sometimes make will automatically run aclocal, you need a way to specify
these arguments. You can do this by defining ACLOCAL_AMFLAGS; this holds arguments that
are passed verbatim to aclocal. This variable is only useful in the top-level Makefile.am.
Sometimes it is convenient to supplement the rebuild rules for configure or
config.status with additional dependencies. The variables CONFIGURE_DEPENDENCIES
and CONFIG_STATUS_DEPENDENCIES can be used to list these extra dependencies. These
variable should be defined in all Makefiles of the tree (because these two rebuild rules are
output in all them), so it is safer and easier to AC_SUBST them from configure.ac. For
instance, the following statement will cause configure to be rerun each time version.sh
is changed.
AC_SUBST([CONFIG_STATUS_DEPENDENCIES], [’$(top_srcdir)/version.sh’])
Chapter 17: Changing Automake’s Behavior 99
Note the ‘$(top_srcdir)/’ in the file name. Since this variable is to be used in all
Makefiles, its value must be sensible at any level in the build hierarchy.
Beware not to mistake CONFIGURE_DEPENDENCIES for CONFIG_STATUS_DEPENDENCIES.
CONFIGURE_DEPENDENCIES adds dependencies to the configure rule, whose effect is to
run autoconf. This variable should be seldom used, because automake already tracks m4_
included files. However it can be useful when playing tricky games with m4_esyscmd or
similar non-recommendable macros with side effects.
CONFIG_STATUS_DEPENDENCIES adds dependencies to the config.status rule, whose
effect is to run configure. This variable should therefore carry any non-standard source
that may be read as a side effect of running configure, like version.sh in the example
above.
Speaking of version.sh scripts, we recommend against them today. They are mainly
used when the version of a package is updated automatically by a script (e.g., in daily
builds). Here is what some old-style configure.acs may look like:
AC_INIT
. $srcdir/version.sh
AM_INIT_AUTOMAKE([name], $VERSION_NUMBER)
...
Here, version.sh is a shell fragment that sets VERSION_NUMBER. The problem with this ex-
ample is that automake cannot track dependencies (listing version.sh in CONFIG_STATUS_
DEPENDENCIES, and distributing this file is up to the user), and that it uses the obsolete
form of AC_INIT and AM_INIT_AUTOMAKE. Upgrading to the new syntax is not straightfor-
ward, because shell variables are not allowed in AC_INIT’s arguments. We recommend that
version.sh be replaced by an M4 file that is included by configure.ac:
m4_include([version.m4])
AC_INIT([name], VERSION_NUMBER)
AM_INIT_AUTOMAKE
...
Here version.m4 could contain something like ‘m4_define([VERSION_NUMBER], [1.2])’.
The advantage of this second form is that automake will take care of the dependencies when
defining the rebuild rule, and will also distribute the file automatically. An inconvenience
is that autoconf will now be rerun each time the version number is bumped, when only
configure had to be rerun in the previous setup.
17 Changing Automake’s Behavior
Various features of Automake can be controlled by options in the Makefile.am. Such
options are applied on a per-Makefile basis when listed in a special Makefile variable
named AUTOMAKE_OPTIONS. They are applied globally to all processed Makefiles when
listed in the first argument of AM_INIT_AUTOMAKE in configure.ac. Currently understood
options are:
gnits
gnu
foreign
cygnus
Chapter 17: Changing Automake’s Behavior 100
Set the strictness as appropriate. The gnits option also implies options
readme-alpha and check-news.
ansi2knr
path/ansi2knr
Turn on the obsolete de-ANSI-fication feature. See Section 8.17 [ANSI], page 76.
If preceded by a path, the generated Makefile.in will look in the specified
directory to find the ansi2knr program. The path should be a relative path to
another directory in the same distribution (Automake currently does not check
this).
check-news
Cause ‘make dist’ to fail unless the current version number appears in the first
few lines of the NEWS file.
color-tests
Cause output of the simple test suite (see Chapter 15 [Tests], page 97) to be
colorized on capable terminals.
dejagnu Cause dejagnu-specific rules to be generated. See Chapter 15 [Tests], page 97.
dist-bzip2
Hook dist-bzip2 to dist.
dist-lzma
Hook dist-lzma to dist.
dist-shar
Hook dist-shar to dist.
dist-zip Hook dist-zip to dist.
dist-tarZ
Hook dist-tarZ to dist.
filename-length-max=99
Abort if file names longer than 99 characters are found during ‘make dist’. Such
long file names are generally considered not to be portable in tarballs. See the
tar-v7 and tar-ustar options below. This option should be used in the top-
level Makefile.am or as an argument of AM_INIT_AUTOMAKE in configure.ac,
it will be ignored otherwise. It will also be ignored in sub-packages of nested
packages (see Section 7.4 [Subpackages], page 49).
no-define
This options is meaningful only when passed as an argument to AM_INIT_
AUTOMAKE. It will prevent the PACKAGE and VERSION variables to be AC_DEFINEd.
no-dependencies
This is similar to using --ignore-deps on the command line, but is useful for
those situations where you don’t have the necessary bits to make automatic
dependency tracking work (see Section 8.18 [Dependencies], page 77). In this
case the effect is to effectively disable automatic dependency tracking.
no-dist Don’t emit any code related to dist target. This is useful when a package has
its own method for making distributions.
Chapter 17: Changing Automake’s Behavior 101
no-dist-gzip
Do not hook dist-gzip to dist.
no-exeext
If your Makefile.am defines a rule for target foo, it will override a rule for a
target named ‘foo$(EXEEXT)’. This is necessary when EXEEXT is found to be
empty. However, by default automake will generate an error for this use. The
no-exeext option will disable this error. This is intended for use only where
it is known in advance that the package will not be ported to Windows, or any
other operating system using extensions on executables.
no-installinfo
The generated Makefile.in will not cause info pages to be built or installed by
default. However, info and install-info targets will still be available. This
option is disallowed at gnu strictness and above.
no-installman
The generated Makefile.in will not cause man pages to be installed by default.
However, an install-man target will still be available for optional installation.
This option is disallowed at gnu strictness and above.
nostdinc This option can be used to disable the standard -I options that are ordinarily
automatically provided by Automake.
no-texinfo.tex
Don’t require texinfo.tex, even if there are texinfo files in this directory.
readme-alpha
If this release is an alpha release, and the file README-alpha exists, then it
will be added to the distribution. If this option is given, version numbers are
expected to follow one of two forms. The first form is ‘MAJOR.MINOR.ALPHA’,
where each element is a number; the final period and number should be left off
for non-alpha releases. The second form is ‘MAJOR.MINORALPHA’, where ALPHA
is a letter; it should be omitted for non-alpha releases.
std-options
Make the installcheck rule check that installed scripts and programs support
the --help and --version options. This also provides a basic check that the
program’s run-time dependencies are satisfied after installation.
In a few situations, programs (or scripts) have to be exempted from this test.
For instance, false (from GNU sh-utils) is never successful, even for --help
or --version. You can list such programs in the variable AM_INSTALLCHECK_
STD_OPTIONS_EXEMPT. Programs (not scripts) listed in this variable should be
suffixed by ‘$(EXEEXT)’ for the sake of Win32 or OS/2. For instance, suppose
we build false as a program but true.sh as a script, and that neither of them
support --help or --version:
AUTOMAKE_OPTIONS = std-options
bin_PROGRAMS = false ...
bin_SCRIPTS = true.sh ...
AM_INSTALLCHECK_STD_OPTIONS_EXEMPT = false$(EXEEXT) true.sh
Chapter 17: Changing Automake’s Behavior 102
subdir-objects
If this option is specified, then objects are placed into the subdirectory of the
build directory corresponding to the subdirectory of the source file. For in-
stance, if the source file is subdir/file.cxx, then the output file would be
subdir/file.o.
In order to use this option with C sources, you should add AM_PROG_CC_C_O to
configure.ac.
tar-v7
tar-ustar
tar-pax
These three mutually exclusive options select the tar format to use when gen-
erating tarballs with ‘make dist’. (The tar file created is then compressed
according to the set of no-dist-gzip, dist-bzip2, dist-lzma and dist-tarZ
options in use.)
These options must be passed as argument to AM_INIT_AUTOMAKE (see
Section 6.4 [Macros], page 42) because they can require additional configure
checks. Automake will complain if it sees such options in an AUTOMAKE_OPTIONS
variable.
tar-v7 selects the old V7 tar format. This is the historical default. This anti-
quated format is understood by all tar implementations and supports file names
with up to 99 characters. When given longer file names some tar implementa-
tions will diagnose the problem while other will generate broken tarballs or use
non-portable extensions. Furthermore, the V7 format cannot store empty direc-
tories. When using this format, consider using the filename-length-max=99
option to catch file names too long.
tar-ustar selects the ustar format defined by POSIX 1003.1-1988. This format
is believed to be old enough to be portable. It fully supports empty directories.
It can store file names with up to 256 characters, provided that the file name
can be split at directory separator in two parts, first of them being at most 155
bytes long. So, in most cases the maximum file name length will be shorter
than 256 characters. However you may run against broken tar implementations
that incorrectly handle file names longer than 99 characters (please report them
to bug-automake@gnu.org so we can document this accurately).
tar-pax selects the new pax interchange format defined by POSIX 1003.1-2001.
It does not limit the length of file names. However, this format is very young
and should probably be restricted to packages that target only very modern
platforms. There are moves to change the pax format in an upward-compatible
way, so this option may refer to a more recent version in the future.
See Section “Controlling the Archive Format” in GNU Tar, for further discus-
sion about tar formats.
configure knows several ways to construct these formats. It will not abort if
it cannot find a tool up to the task (so that the package can still be built), but
‘make dist’ will fail.
version A version number (e.g., ‘0.30’) can be specified. If Automake is not newer than
the version specified, creation of the Makefile.in will be suppressed.
Chapter 18: Miscellaneous Rules 103
-Wcategory or --warnings=category
These options behave exactly like their command-line counterpart (see
Chapter 5 [Invoking Automake], page 25). This allows you to enable or disable
some warning categories on a per-file basis. You can also setup some warnings
for your entire project; for instance, try ‘AM_INIT_AUTOMAKE([-Wall])’ in
your configure.ac.
Unrecognized options are diagnosed by automake.
If you want an option to apply to all the files in the tree, you can use the AM_INIT_
AUTOMAKE macro in configure.ac. See Section 6.4 [Macros], page 42.
18 Miscellaneous Rules
There are a few rules and variables that didn’t fit anywhere else.
18.1 Interfacing to etags
Automake will generate rules to generate TAGS files for use with GNU Emacs under some
circumstances.
If any C, C++ or Fortran 77 source code or headers are present, then tags and TAGS
rules will be generated for the directory. All files listed using the _SOURCES, _HEADERS, and
_LISP primaries will be used to generate tags. Note that generated source files that are not
distributed must be declared in variables like nodist_noinst_HEADERS or nodist_prog_
SOURCES or they will be ignored.
A tags rule will be output at the topmost directory of a multi-directory package. When
run from this topmost directory, ‘make tags’ will generate a TAGS file that includes by
reference all TAGS files from subdirectories.
The tags rule will also be generated if the variable ETAGS_ARGS is defined. This variable
is intended for use in directories that contain taggable source that etags does not under-
stand. The user can use the ETAGSFLAGS to pass additional flags to etags; AM_ETAGSFLAGS
is also available for use in Makefile.am.
Here is how Automake generates tags for its source, and for nodes in its Texinfo file:
ETAGS_ARGS = automake.in --lang=none \
--regex=’/^@node[ \t]+\([^,]+\)/\1/’ automake.texi
If you add file names to ETAGS_ARGS, you will probably also want to define TAGS_
DEPENDENCIES. The contents of this variable are added directly to the dependencies for
the tags rule.
Automake also generates a ctags rule that can be used to build vi-style tags files.
The variable CTAGS is the name of the program to invoke (by default ctags); CTAGSFLAGS
can be used by the user to pass additional flags, and AM_CTAGSFLAGS can be used by the
Makefile.am.
Automake will also generate an ID rule that will run mkid on the source. This is only
supported on a directory-by-directory basis.
Finally, Automake also emit rules to support the GNU Global Tags program (http://
www.gnu.org/software/global/). The GTAGS rule runs Global Tags and puts the result
Chapter 19: Include 104
in the top build directory. The variable GTAGS_ARGS holds arguments that are passed to
gtags.
18.2 Handling new file extensions
It is sometimes useful to introduce a new implicit rule to handle a file type that Automake
does not know about.
For instance, suppose you had a compiler that could compile .foo files to .o files. You
would simply define an suffix rule for your language:
.foo.o:
foocc -c -o $@ $<
Then you could directly use a .foo file in a _SOURCES variable and expect the correct
results:
bin_PROGRAMS = doit
doit_SOURCES = doit.foo
This was the simpler and more common case. In other cases, you will have to help
Automake to figure which extensions you are defining your suffix rule for. This usually
happens when your extensions does not start with a dot. Then, all you have to do is to put
a list of new suffixes in the SUFFIXES variable before you define your implicit rule.
For instance, the following definition prevents Automake to misinterpret ‘.idlC.cpp:’
as an attempt to transform .idlC files into .cpp files.
SUFFIXES = .idl C.cpp
.idlC.cpp:
# whatever
As you may have noted, the SUFFIXES variable behaves like the .SUFFIXES special target
of make. You should not touch .SUFFIXES yourself, but use SUFFIXES instead and let
Automake generate the suffix list for .SUFFIXES. Any given SUFFIXES go at the start of
the generated suffixes list, followed by Automake generated suffixes not already in the list.
18.3 Support for Multilibs
Automake has support for an obscure feature called multilibs. A multilib is a library that
is built for multiple different ABIs at a single time; each time the library is built with a
different target flag combination. This is only useful when the library is intended to be
cross-compiled, and it is almost exclusively used for compiler support libraries.
The multilib support is still experimental. Only use it if you are familiar with multilibs
and can debug problems you might encounter.
19 Include
Automake supports an include directive that can be used to include other Makefile frag-
ments when automake is run. Note that these fragments are read and interpreted by
automake, not by make. As with conditionals, make has no idea that include is in use.
Chapter 20: Conditionals 105
There are two forms of include:
include $(srcdir)/file
Include a fragment that is found relative to the current source directory.
include $(top_srcdir)/file
Include a fragment that is found relative to the top source directory.
Note that if a fragment is included inside a conditional, then the condition applies to
the entire contents of that fragment.
Makefile fragments included this way are always distributed because they are needed to
rebuild Makefile.in.
20 Conditionals
Automake supports a simple type of conditionals.
Usage
Before using a conditional, you must define it by using AM_CONDITIONAL in the
configure.ac file (see Section 6.4 [Macros], page 42).
AM_CONDITIONAL (conditional, condition) [Macro]
The conditional name, conditional, should be a simple string starting with a letter
and containing only letters, digits, and underscores. It must be different from ‘TRUE’
and ‘FALSE’ that are reserved by Automake.
The shell condition (suitable for use in a shell if statement) is evaluated when
configure is run. Note that you must arrange for every AM_CONDITIONAL to be
invoked every time configure is run. If AM_CONDITIONAL is run conditionally (e.g.,
in a shell if statement), then the result will confuse automake.
Conditionals typically depend upon options that the user provides to the configure
script. Here is an example of how to write a conditional that is true if the user uses the
--enable-debug option.
AC_ARG_ENABLE([debug],
[ --enable-debug Turn on debugging],
[case "${enableval}" in
yes) debug=true ;;
no) debug=false ;;
*) AC_MSG_ERROR([bad value ${enableval} for --enable-debug]) ;;
esac],[debug=false])
AM_CONDITIONAL([DEBUG], [test x$debug = xtrue])
Here is an example of how to use that conditional in Makefile.am:
if DEBUG
DBG = debug
else
DBG =
endif
Chapter 20: Conditionals 106
noinst_PROGRAMS = $(DBG)
This trivial example could also be handled using EXTRA_PROGRAMS (see Section 8.1.4
[Conditional Programs], page 54).
You may only test a single variable in an if statement, possibly negated using ‘!’. The
else statement may be omitted. Conditionals may be nested to any depth. You may
specify an argument to else in which case it must be the negation of the condition used
for the current if. Similarly you may specify the condition that is closed by an end:
if DEBUG
DBG = debug
else !DEBUG
DBG =
endif !DEBUG
Unbalanced conditions are errors.
The else branch of the above two examples could be omitted, since assigning the empty
string to an otherwise undefined variable makes no difference.
In order to allow access to the condition registered by AM_CONDITIONAL inside
configure.ac, and to allow conditional AC_CONFIG_FILES, AM_COND_IF may be used:
AM_COND_IF (conditional, [if-true], [if-false]) [Macro]
If conditional is fulfilled, execute if-true, otherwise execute if-false. If either branch
contains AC_CONFIG_FILES, it will cause automake to output the rules for the respec-
tive files only for the given condition.
AM_COND_IF macros may be nested when m4 quotation is used properly (see Section “M4
Quotation” in The Autoconf Manual).
Here is an example of how to define a conditional config file:
AM_CONDITIONAL([SHELL_WRAPPER], [test "x$with_wrapper" = xtrue])
AM_COND_IF([SHELL_WRAPPER],
[AC_CONFIG_FILES([wrapper:wrapper.in])])
Portability
Note that conditionals in Automake are not the same as conditionals in GNU Make. Au-
tomake conditionals are checked at configure time by the configure script, and affect the
translation from Makefile.in to Makefile. They are based on options passed to configure
and on results that configure has discovered about the host system. GNU Make condi-
tionals are checked at make time, and are based on variables passed to the make program
or defined in the Makefile.
Automake conditionals will work with any make program.
Limits
Conditionals should enclose complete statements like variables or rules definitions. Au-
tomake cannot deal with conditionals used inside a variable definition, for instance, and is
not even able to diagnose this situation. The following example would not work:
# This syntax is not understood by Automake
Chapter 21: The effect of --gnu and --gnits 107
AM_CPPFLAGS = \
-DFEATURE_A \
if WANT_DEBUG
-DDEBUG \
endif
-DFEATURE_B
However the intended definition of AM_CPPFLAGS can be achieved with
if WANT_DEBUG
DEBUGFLAGS = -DDEBUG
endif
AM_CPPFLAGS = -DFEATURE_A $(DEBUGFLAGS) -DFEATURE_B
or
AM_CPPFLAGS = -DFEATURE_A
if WANT_DEBUG
AM_CPPFLAGS += -DDEBUG
endif
AM_CPPFLAGS += -DFEATURE_B
21 The effect of --gnu and --gnits
The --gnu option (or gnu in the AUTOMAKE_OPTIONS variable) causes automake to check the
following:
• The files INSTALL, NEWS, README, AUTHORS, and ChangeLog, plus one of COPYING.LIB,
COPYING.LESSER or COPYING, are required at the topmost directory of the package.
If the --add-missing option is given, automake will add a generic version of the
INSTALL file as well as the COPYING file containing the text of the current version of the
GNU General Public License existing at the time of this Automake release (version 3
as this is written, http://www.gnu.org/copyleft/gpl.html). However, an existing
COPYING file will never be overwritten by automake.
• The options no-installman and no-installinfo are prohibited.
Note that this option will be extended in the future to do even more checking; it is
advisable to be familiar with the precise requirements of the GNU standards. Also, --gnu
can require certain non-standard GNU programs to exist for use by various maintainer-only
rules; for instance, in the future pathchk might be required for ‘make dist’.
The --gnits option does everything that --gnu does, and checks the following as well:
• ‘make installcheck’ will check to make sure that the --help and --version really
print a usage message and a version string, respectively. This is the std-options
option (see Chapter 17 [Options], page 99).
• ‘make dist’ will check to make sure the NEWS file has been updated to the current
version.
• VERSION is checked to make sure its format complies with Gnits standards.
• If VERSION indicates that this is an alpha release, and the file README-alpha appears
in the topmost directory of a package, then it is included in the distribution. This
Chapter 23: When Automake Isn’t Enough 108
is done in --gnits mode, and no other, because this mode is the only one where
version number formats are constrained, and hence the only mode where Automake
can automatically determine whether README-alpha should be included.
• The file THANKS is required.
22 The effect of --cygnus
Some packages, notably GNU GCC and GNU gdb, have a build environment originally
written at Cygnus Support (subsequently renamed Cygnus Solutions, and then later pur-
chased by Red Hat). Packages with this ancestry are sometimes referred to as “Cygnus”
trees.
A Cygnus tree has slightly different rules for how a Makefile.in is to be constructed.
Passing --cygnus to automake will cause any generated Makefile.in to comply with
Cygnus rules.
Here are the precise effects of --cygnus:
• Info files are always created in the build directory, and not in the source directory.
• texinfo.tex is not required if a Texinfo source file is specified. The assumption is that
the file will be supplied, but in a place that Automake cannot find. This assumption
is an artifact of how Cygnus packages are typically bundled.
• ‘make dist’ is not supported, and the rules for it are not generated. Cygnus-style trees
use their own distribution mechanism.
• Certain tools will be searched for in the build tree as well as in the user’s PATH. These
tools are runtest, expect, makeinfo and texi2dvi.
• --foreign is implied.
• The options no-installinfo and no-dependencies are implied.
• The macros AM_MAINTAINER_MODE and AM_CYGWIN32 are required.
• The check target doesn’t depend on all.
GNU maintainers are advised to use gnu strictness in preference to the special Cygnus
mode. Some day, perhaps, the differences between Cygnus trees and GNU trees will disap-
pear (for instance, as GCC is made more standards compliant). At that time the special
Cygnus mode will be removed.
23 When Automake Isn’t Enough
In some situations, where Automake is not up to one task, one has to resort to handwritten
rules or even handwritten Makefiles.
23.1 Extending Automake Rules
With some minor exceptions (for example _PROGRAMS variables, TESTS, or XFAIL_TESTS)
being rewritten to append ‘$(EXEEXT)’), the contents of a Makefile.am is copied to
Makefile.in verbatim.
Chapter 23: When Automake Isn’t Enough 109
These copying semantics means that many problems can be worked around by simply
adding some make variables and rules to Makefile.am. Automake will ignore these addi-
tions.
Since a Makefile.in is built from data gathered from three different places
(Makefile.am, configure.ac, and automake itself), it is possible to have conflicting
definitions of rules or variables. When building Makefile.in the following priorities
are respected by automake to ensure the user always have the last word. User defined
variables in Makefile.am have priority over variables AC_SUBSTed from configure.ac,
and AC_SUBSTed variables have priority over automake-defined variables. As far rules are
concerned, a user-defined rule overrides any automake-defined rule for the same target.
These overriding semantics make it possible to fine tune some default settings of Au-
tomake, or replace some of its rules. Overriding Automake rules is often inadvisable, par-
ticularly in the topmost directory of a package with subdirectories. The -Woverride option
(see Chapter 5 [Invoking Automake], page 25) comes handy to catch overridden definitions.
Note that Automake does not make any difference between rules with commands and
rules that only specify dependencies. So it is not possible to append new dependencies to
an automake-defined target without redefining the entire rule.
However, various useful targets have a ‘-local’ version you can specify in your
Makefile.am. Automake will supplement the standard target with these user-supplied
targets.
The targets that support a local version are all, info, dvi, ps, pdf, html,
check, install-data, install-dvi, install-exec, install-html, install-info,
install-pdf, install-ps, uninstall, installdirs, installcheck and the various
clean targets (mostlyclean, clean, distclean, and maintainer-clean).
Note that there are no uninstall-exec-local or uninstall-data-local targets; just
use uninstall-local. It doesn’t make sense to uninstall just data or just executables.
For instance, here is one way to erase a subdirectory during ‘make clean’ (see Chapter 13
[Clean], page 93).
clean-local:
-rm -rf testSubDir
You may be tempted to use install-data-local to install a file to some hard-coded
location, but you should avoid this (see Section 27.10 [Hard-Coded Install Paths], page 129).
With the -local targets, there is no particular guarantee of execution order; typically,
they are run early, but with parallel make, there is no way to be sure of that.
In contrast, some rules also have a way to run another rule, called a hook; hooks are al-
ways executed after the main rule’s work is done. The hook is named after the principal tar-
get, with ‘-hook’ appended. The targets allowing hooks are install-data, install-exec,
uninstall, dist, and distcheck.
For instance, here is how to create a hard link to an installed program:
install-exec-hook:
ln $(DESTDIR)$(bindir)/program$(EXEEXT) \
$(DESTDIR)$(bindir)/proglink$(EXEEXT)
Although cheaper and more portable than symbolic links, hard links will not work ev-
erywhere (for instance, OS/2 does not have ln). Ideally you should fall back to ‘cp -p’
Chapter 23: When Automake Isn’t Enough 110
when ln does not work. An easy way, if symbolic links are acceptable to you, is to add AC_
PROG_LN_S to configure.ac (see Section “Particular Program Checks” in The Autoconf
Manual) and use ‘$(LN_S)’ in Makefile.am.
For instance, here is how you could install a versioned copy of a program using ‘$(LN_S)’:
install-exec-hook:
cd $(DESTDIR)$(bindir) && \
mv -f prog$(EXEEXT) prog-$(VERSION)$(EXEEXT) && \
$(LN_S) prog-$(VERSION)$(EXEEXT) prog$(EXEEXT)
Note that we rename the program so that a new version will erase the symbolic link, not
the real binary. Also we cd into the destination directory in order to create relative links.
When writing install-exec-hook or install-data-hook, please bear in mind that
the exec/data distinction is based on the installation directory, not on the primary used
(see Chapter 12 [Install], page 91). So a foo_SCRIPTS will be installed by install-data,
and a barexec_SCRIPTS will be installed by install-exec. You should define your hooks
consequently.
23.2 Third-Party Makefiles
In most projects all Makefiles are generated by Automake. In some cases, however, projects
need to embed subdirectories with handwritten Makefiles. For instance, one subdirectory
could be a third-party project with its own build system, not using Automake.
It is possible to list arbitrary directories in SUBDIRS or DIST_SUBDIRS provided each of
these directories has a Makefile that recognizes all the following recursive targets.
When a user runs one of these targets, that target is run recursively in all subdirectories.
This is why it is important that even third-party Makefiles support them.
all Compile the entire package. This is the default target in Automake-generated
Makefiles, but it does not need to be the default in third-party Makefiles.
distdir Copy files to distribute into ‘$(distdir)’, before a tarball is constructed. Of
course this target is not required if the no-dist option (see Chapter 17 [Op-
tions], page 99) is used.
The variables ‘$(top_distdir)’ and ‘$(distdir)’ (see Chapter 14 [Dist],
page 93) will be passed from the outer package to the subpackage when the
distdir target is invoked. These two variables have been adjusted for the
directory that is being recursed into, so they are ready to use.
install
install-data
install-exec
uninstall
Install or uninstall files (see Chapter 12 [Install], page 91).
Chapter 23: When Automake Isn’t Enough 111
install-dvi
install-html
install-info
install-ps
install-pdf
Install only some specific documentation format (see Section 11.1 [Texinfo],
page 88).
installdirs
Create install directories, but do not install any files.
check
installcheck
Check the package (see Chapter 15 [Tests], page 97).
mostlyclean
clean
distclean
maintainer-clean
Cleaning rules (see Chapter 13 [Clean], page 93).
dvi
pdf
ps
info
html Build the documentation in various formats (see Section 11.1 [Texinfo],
page 88).
tags
ctags Build TAGS and CTAGS (see Section 18.1 [Tags], page 103).
If you have ever used Gettext in a project, this is a good example of how third-party
Makefiles can be used with Automake. The Makefiles gettextize puts in the po/ and
intl/ directories are handwritten Makefiles that implement all these targets. That way
they can be added to SUBDIRS in Automake packages.
Directories that are only listed in DIST_SUBDIRS but not in SUBDIRS need only the
distclean, maintainer-clean, and distdir rules (see Section 7.2 [Conditional Subdirec-
tories], page 46).
Usually, many of these rules are irrelevant to the third-party subproject, but they are
required for the whole package to work. It’s OK to have a rule that does nothing, so if
you are integrating a third-party project with no documentation or tag support, you could
simply augment its Makefile as follows:
EMPTY_AUTOMAKE_TARGETS = dvi pdf ps info html tags ctags
.PHONY: $(EMPTY_AUTOMAKE_TARGETS)
$(EMPTY_AUTOMAKE_TARGETS):
Another aspect of integrating third-party build systems is whether they support VPATH
builds (see Section 2.2.6 [VPATH Builds], page 6). Obviously if the subpackage does not sup-
port VPATH builds the whole package will not support VPATH builds. This in turns means
that ‘make distcheck’ will not work, because it relies on VPATH builds. Some people can
Chapter 23: When Automake Isn’t Enough 112
live without this (actually, many Automake users have never heard of ‘make distcheck’).
Other people may prefer to revamp the existing Makefiles to support VPATH. Doing so
does not necessarily require Automake, only Autoconf is needed (see Section “Build Directo-
ries” in The Autoconf Manual). The necessary substitutions: ‘@srcdir@’, ‘@top_srcdir@’,
and ‘@top_builddir@’ are defined by configure when it processes a Makefile (see Section
“Preset Output Variables” in The Autoconf Manual), they are not computed by the Make-
file like the aforementioned ‘$(distdir)’ and ‘$(top_distdir)’ variables..
It is sometimes inconvenient to modify a third-party Makefile to introduce the above
required targets. For instance, one may want to keep the third-party sources untouched to
ease upgrades to new versions.
Here are two other ideas. If GNU make is assumed, one possibility is to add to that
subdirectory a GNUmakefile that defines the required targets and include the third-party
Makefile. For this to work in VPATH builds, GNUmakefile must lie in the build directory;
the easiest way to do this is to write a GNUmakefile.in instead, and have it processed with
AC_CONFIG_FILES from the outer package. For example if we assume Makefile defines all
targets except the documentation targets, and that the check target is actually called test,
we could write GNUmakefile (or GNUmakefile.in) like this:
# First, include the real Makefile
include Makefile
# Then, define the other targets needed by Automake Makefiles.
.PHONY: dvi pdf ps info html check
dvi pdf ps info html:
check: test
A similar idea that does not use include is to write a proxy Makefile that dispatches
rules to the real Makefile, either with ‘$(MAKE) -f Makefile.real $(AM_MAKEFLAGS)
target’ (if it’s OK to rename the original Makefile) or with ‘cd subdir && $(MAKE)
$(AM_MAKEFLAGS) target’ (if it’s OK to store the subdirectory project one directory
deeper). The good news is that this proxy Makefile can be generated with Automake.
All we need are -local targets (see Section 23.1 [Extending], page 108) that perform the
dispatch. Of course the other Automake features are available, so you could decide to let
Automake perform distribution or installation. Here is a possible Makefile.am:
all-local:
cd subdir && $(MAKE) $(AM_MAKEFLAGS) all
check-local:
cd subdir && $(MAKE) $(AM_MAKEFLAGS) test
clean-local:
cd subdir && $(MAKE) $(AM_MAKEFLAGS) clean
# Assuming the package knows how to install itself
install-data-local:
cd subdir && $(MAKE) $(AM_MAKEFLAGS) install-data
install-exec-local:
cd subdir && $(MAKE) $(AM_MAKEFLAGS) install-exec
uninstall-local:
cd subdir && $(MAKE) $(AM_MAKEFLAGS) uninstall
Chapter 25: Automake API versioning 113
# Distribute files from here.
EXTRA_DIST = subdir/Makefile subdir/program.c ...
Pushing this idea to the extreme, it is also possible to ignore the subproject build system
and build everything from this proxy Makefile.am. This might sounds very sensible if you
need VPATH builds but the subproject does not support them.
24 Distributing Makefile.ins
Automake places no restrictions on the distribution of the resulting Makefile.ins. We still
encourage software authors to distribute their work under terms like those of the GPL, but
doing so is not required to use Automake.
Some of the files that can be automatically installed via the --add-missing switch do
fall under the GPL. However, these also have a special exception allowing you to distribute
them with your package, regardless of the licensing you choose.
25 Automake API versioning
New Automake releases usually include bug fixes and new features. Unfortunately they
may also introduce new bugs and incompatibilities. This makes four reasons why a package
may require a particular Automake version.
Things get worse when maintaining a large tree of packages, each one requiring a different
version of Automake. In the past, this meant that any developer (and sometime users) had
to install several versions of Automake in different places, and switch ‘$PATH’ appropriately
for each package.
Starting with version 1.6, Automake installs versioned binaries. This means you can
install several versions of Automake in the same ‘$prefix’, and can select an arbitrary Au-
tomake version by running automake-1.6 or automake-1.7 without juggling with ‘$PATH’.
Furthermore, Makefile’s generated by Automake 1.6 will use automake-1.6 explicitly in
their rebuild rules.
The number ‘1.6’ in automake-1.6 is Automake’s API version, not Automake’s version.
If a bug fix release is made, for instance Automake 1.6.1, the API version will remain 1.6.
This means that a package that works with Automake 1.6 should also work with 1.6.1; after
all, this is what people expect from bug fix releases.
If your package relies on a feature or a bug fix introduced in a release, you can pass this
version as an option to Automake to ensure older releases will not be used. For instance,
use this in your configure.ac:
AM_INIT_AUTOMAKE([1.6.1]) dnl Require Automake 1.6.1 or better.
or, in a particular Makefile.am:
AUTOMAKE_OPTIONS = 1.6.1 # Require Automake 1.6.1 or better.
Automake will print an error message if its version is older than the requested version.
Chapter 26: Upgrading a Package to a Newer Automake Version 114
What is in the API
Automake’s programming interface is not easy to define. Basically it should include at least
all documented variables and targets that a Makefile.am author can use, any behavior
associated with them (e.g., the places where ‘-hook’’s are run), the command line interface
of automake and aclocal, . . .
What is not in the API
Every undocumented variable, target, or command line option, is not part of the API. You
should avoid using them, as they could change from one version to the other (even in bug
fix releases, if this helps to fix a bug).
If it turns out you need to use such a undocumented feature, contact automake@gnu.org
and try to get it documented and exercised by the test-suite.
26 Upgrading a Package to a Newer Automake
Version
Automake maintains three kind of files in a package.
• aclocal.m4
• Makefile.ins
• auxiliary tools like install-sh or py-compile
aclocal.m4 is generated by aclocal and contains some Automake-supplied M4 macros.
Auxiliary tools are installed by ‘automake --add-missing’ when needed. Makefile.ins
are built from Makefile.am by automake, and rely on the definitions of the M4 macros put
in aclocal.m4 as well as the behavior of the auxiliary tools installed.
Because all these files are closely related, it is important to regenerate all of them when
upgrading to a newer Automake release. The usual way to do that is
aclocal # with any option needed (such a -I m4)
autoconf
automake --add-missing --force-missing
or more conveniently:
autoreconf -vfi
The use of --force-missing ensures that auxiliary tools will be overridden by new
versions (see Chapter 5 [Invoking Automake], page 25).
It is important to regenerate all these files each time Automake is upgraded, even between
bug fixes releases. For instance, it is not unusual for a bug fix to involve changes to both
the rules generated in Makefile.in and the supporting M4 macros copied to aclocal.m4.
Presently automake is able to diagnose situations where aclocal.m4 has been generated
with another version of aclocal. However it never checks whether auxiliary scripts are
up-to-date. In other words, automake will tell you when aclocal needs to be rerun, but it
will never diagnose a missing --force-missing.
Before upgrading to a new major release, it is a good idea to read the file NEWS. This
file lists all changes between releases: new features, obsolete constructs, known incompati-
bilities, and workarounds.
Chapter 27: Frequently Asked Questions about Automake 115
27 Frequently Asked Questions about Automake
This chapter covers some questions that often come up on the mailing lists.
27.1 CVS and generated files
27.1.1 Background: distributed generated files
Packages made with Autoconf and Automake ship with some generated files like configure
or Makefile.in. These files were generated on the developer’s host and are distributed
so that end-users do not have to install the maintainer tools required to rebuild them.
Other generated files like Lex scanners, Yacc parsers, or Info documentation, are usually
distributed on similar grounds.
Automake outputs rules in Makefiles to rebuild these files. For instance, make will run
autoconf to rebuild configure whenever configure.ac is changed. This makes develop-
ment safer by ensuring a configure is never out-of-date with respect to configure.ac.
As generated files shipped in packages are up-to-date, and because tar preserves times-
tamps, these rebuild rules are not triggered when a user unpacks and builds a package.
27.1.2 Background: CVS and timestamps
Unless you use CVS keywords (in which case files must be updated at commit time), CVS
preserves timestamp during ‘cvs commit’ and ‘cvs import -d’ operations.
When you check out a file using ‘cvs checkout’ its timestamp is set to that of the
revision that is being checked out.
However, during cvs update, files will have the date of the update, not the original
timestamp of this revision. This is meant to make sure that make notices sources files have
been updated.
This timestamp shift is troublesome when both sources and generated files are kept under
CVS. Because CVS processes files in lexical order, configure.ac will appear newer than
configure after a cvs update that updates both files, even if configure was newer than
configure.ac when it was checked in. Calling make will then trigger a spurious rebuild of
configure.
27.1.3 Living with CVS in Autoconfiscated projects
There are basically two clans amongst maintainers: those who keep all distributed files
under CVS, including generated files, and those who keep generated files out of CVS.
All files in CVS
• The CVS repository contains all distributed files so you know exactly what is dis-
tributed, and you can checkout any prior version entirely.
• Maintainers can see how generated files evolve (for instance, you can see what happens
to your Makefile.ins when you upgrade Automake and make sure they look OK).
• Users do not need the autotools to build a checkout of the project, it works just like a
released tarball.
Chapter 27: Frequently Asked Questions about Automake 116
• If users use cvs update to update their copy, instead of cvs checkout to fetch a fresh
one, timestamps will be inaccurate. Some rebuild rules will be triggered and attempt
to run developer tools such as autoconf or automake.
Actually, calls to such tools are all wrapped into a call to the missing script discussed
later (see Section 27.2 [maintainer-mode], page 117). missing will take care of fixing
the timestamps when these tools are not installed, so that the build can continue.
• In distributed development, developers are likely to have different version of the main-
tainer tools installed. In this case rebuilds triggered by timestamp lossage will lead to
spurious changes to generated files. There are several solutions to this:
• All developers should use the same versions, so that the rebuilt files are identical
to files in CVS. (This starts to be difficult when each project you work on uses
different versions.)
• Or people use a script to fix the timestamp after a checkout (the GCC folks have
such a script).
• Or configure.ac uses AM_MAINTAINER_MODE, which will disable all these rebuild
rules by default. This is further discussed in Section 27.2 [maintainer-mode],
page 117.
• Although we focused on spurious rebuilds, the converse can also happen. CVS’s time-
stamp handling can also let you think an out-of-date file is up-to-date.
For instance, suppose a developer has modified Makefile.am and has rebuilt
Makefile.in. He then decide to do a last-minute change to Makefile.am right before
checking in both files (without rebuilding Makefile.in to account for the change).
This last change to Makefile.am make the copy of Makefile.in out-of-date. Since
CVS processes files alphabetically, when another developer ‘cvs update’ his or her tree,
Makefile.in will happen to be newer than Makefile.am. This other developer will
not see Makefile.in is out-of-date.
Generated files out of CVS
One way to get CVS and make working peacefully is to never store generated files in CVS,
i.e., do not CVS-control files that are Makefile targets (also called derived files).
This way developers are not annoyed by changes to generated files. It does not
matter if they all have different versions (assuming they are compatible, of course).
And finally, timestamps are not lost, changes to sources files can’t be missed as in the
Makefile.am/Makefile.in example discussed earlier.
The drawback is that the CVS repository is not an exact copy of what is distributed
and that users now need to install various development tools (maybe even specific versions)
before they can build a checkout. But, after all, CVS’s job is versioning, not distribution.
Allowing developers to use different versions of their tools can also hide bugs during
distributed development. Indeed, developers will be using (hence testing) their own gen-
erated files, instead of the generated files that will be released actually. The developer
who prepares the tarball might be using a version of the tool that produces bogus output
(for instance a non-portable C file), something other developers could have noticed if they
weren’t using their own versions of this tool.
Chapter 27: Frequently Asked Questions about Automake 117
27.1.4 Third-party files
Another class of files not discussed here (because they do not cause timestamp issues) are
files that are shipped with a package, but maintained elsewhere. For instance, tools like
gettextize and autopoint (from Gettext) or libtoolize (from Libtool), will install or
update files in your package.
These files, whether they are kept under CVS or not, raise similar concerns about version
mismatch between developers’ tools. The Gettext manual has a section about this, see
Section “Integrating with CVS” in GNU gettext tools.
27.2 missing and AM_MAINTAINER_MODE
27.2.1 missing
The missing script is a wrapper around several maintainer tools, designed to warn users if a
maintainer tool is required but missing. Typical maintainer tools are autoconf, automake,
bison, etc. Because file generated by these tools are shipped with the other sources of a
package, these tools shouldn’t be required during a user build and they are not checked for
in configure.
However, if for some reason a rebuild rule is triggered and involves a missing tool,
missing will notice it and warn the user. Besides the warning, when a tool is missing,
missing will attempt to fix timestamps in a way that allows the build to continue. For
instance, missing will touch configure if autoconf is not installed. When all distributed
files are kept under CVS, this feature of missing allows user with no maintainer tools to
build a package off CVS, bypassing any timestamp inconsistency implied by ‘cvs update’.
If the required tool is installed, missing will run it and won’t attempt to continue after
failures. This is correct during development: developers love fixing failures. However, users
with wrong versions of maintainer tools may get an error when the rebuild rule is spuriously
triggered, halting the build. This failure to let the build continue is one of the arguments
of the AM_MAINTAINER_MODE advocates.
27.2.2 AM_MAINTAINER_MODE
AM_MAINTAINER_MODE disables the so called "rebuild rules" by default. If you have
AM_MAINTAINER_MODE in configure.ac, and run ‘./configure && make’, then make will
*never* attempt to rebuilt configure, Makefile.ins, Lex or Yacc outputs, etc. I.e., this
disables build rules for files that are usually distributed and that users should normally
not have to update.
If you run ‘./configure --enable-maintainer-mode’, then these rebuild rules will be
active.
People use AM_MAINTAINER_MODE either because they do want their users (or themselves)
annoyed by timestamps lossage (see Section 27.1 [CVS], page 115), or because they simply
can’t stand the rebuild rules and prefer running maintainer tools explicitly.
AM_MAINTAINER_MODE also allows you to disable some custom build rules conditionally.
Some developers use this feature to disable rules that need exotic tools that users may not
have available.
Several years ago François Pinard pointed out several arguments against this
AM_MAINTAINER_MODE macro. Most of them relate to insecurity. By removing dependencies
Chapter 27: Frequently Asked Questions about Automake 118
you get non-dependable builds: change to sources files can have no effect on generated
files and this can be very confusing when unnoticed. He adds that security shouldn’t be
reserved to maintainers (what --enable-maintainer-mode suggests), on the contrary. If
one user has to modify a Makefile.am, then either Makefile.in should be updated or a
warning should be output (this is what Automake uses missing for) but the last thing you
want is that nothing happens and the user doesn’t notice it (this is what happens when
rebuild rules are disabled by AM_MAINTAINER_MODE).
Jim Meyering, the inventor of the AM_MAINTAINER_MODE macro was swayed by François’s
arguments, and got rid of AM_MAINTAINER_MODE in all of his packages.
Still many people continue to use AM_MAINTAINER_MODE, because it helps them working
on projects where all files are kept under CVS, and because missing isn’t enough if you
have the wrong version of the tools.
27.3 Why doesn’t Automake support wildcards?
Developers are lazy. They would often like to use wildcards in Makefile.ams, so that
they would not need to remember to update Makefile.ams every time they add, delete, or
rename a file.
There are several objections to this:
• When using CVS (or similar) developers need to remember they have to run ‘cvs add’
or ‘cvs rm’ anyway. Updating Makefile.am accordingly quickly becomes a reflex.
Conversely, if your application doesn’t compile because you forgot to add a file in
Makefile.am, it will help you remember to ‘cvs add’ it.
• Using wildcards makes it easy to distribute files by mistake. For instance, some code
a developer is experimenting with (a test case, say) that should not be part of the
distribution.
• Using wildcards it’s easy to omit some files by mistake. For instance, one developer
creates a new file, uses it in many places, but forgets to commit it. Another developer
then checks out the incomplete project and is able to run ‘make dist’ successfully, even
though a file is missing. By listing files, ‘make dist’ will complain.
• Finally, it’s really hard to forget to add a file to Makefile.am: files that are not listed
in Makefile.am are not compiled or installed, so you can’t even test them.
Still, these are philosophical objections, and as such you may disagree, or find enough
value in wildcards to dismiss all of them. Before you start writing a patch against Automake
to teach it about wildcards, let’s see the main technical issue: portability.
Although ‘$(wildcard ...)’ works with GNU make, it is not portable to other make
implementations.
The only way Automake could support $(wildcard ...) is by expending $(wildcard
...) when automake is run. The resulting Makefile.ins would be portable since they
would list all files and not use ‘$(wildcard ...)’. However that means developers would
need to remember to run automake each time they add, delete, or rename files.
Compared to editing Makefile.am, this is a very small gain. Sure, it’s easier and faster
to type ‘automake; make’ than to type ‘emacs Makefile.am; make’. But nobody bothered
enough to write a patch to add support for this syntax. Some people use scripts to generate
file lists in Makefile.am or in separate Makefile fragments.
Chapter 27: Frequently Asked Questions about Automake 119
Even if you don’t care about portability, and are tempted to use ‘$(wildcard ...)’
anyway because you target only GNU Make, you should know there are many places where
Automake need to know exactly which files should be processed. As Automake doesn’t
know how to expand ‘$(wildcard ...)’, you cannot use it in these places. ‘$(wildcard
...)’ is a black box comparable to AC_SUBSTed variables as far Automake is concerned.
You can get warnings about ‘$(wildcard ...’) constructs using the -Wportability
flag.
27.4 Limitations on file names
Automake attempts to support all kinds of file names, even those that contain unusual
characters or are unusually long. However, some limitations are imposed by the underlying
operating system and tools.
Most operating systems prohibit the use of the null byte in file names, and reserve ‘/’ as
a directory separator. Also, they require that file names are properly encoded for the user’s
locale. Automake is subject to these limits.
Portable packages should limit themselves to POSIX file names. These can contain ASCII
letters and digits, ‘_’, ‘.’, and ‘-’. File names consist of components separated by ‘/’. File
name components cannot begin with ‘-’.
Portable POSIX file names cannot contain components that exceed a 14-byte limit, but
nowadays it’s normally safe to assume the more-generous XOPEN limit of 255 bytes. POSIX
limits file names to 255 bytes (XOPEN allows 1023 bytes), but you may want to limit a
source tarball to file names to 99 bytes to avoid interoperability problems with old versions
of tar.
If you depart from these rules (e.g., by using non-ASCII characters in file names, or
by using lengthy file names), your installers may have problems for reasons unrelated to
Automake. However, if this does not concern you, you should know about the limitations
imposed by Automake itself. These limitations are undesirable, but some of them seem to
be inherent to underlying tools like Autoconf, Make, M4, and the shell. They fall into three
categories: install directories, build directories, and file names.
The following characters:
newline " # $ ’ ‘
should not appear in the names of install directories. For example, the operand of
configure’s --prefix option should not contain these characters.
Build directories suffer the same limitations as install directories, and in addition should
not contain the following characters:
& @ \
For example, the full name of the directory containing the source files should not contain
these characters.
Source and installation file names like main.c are limited even further: they should
conform to the POSIX/XOPEN rules described above. In addition, if you plan to port to
non-POSIX environments, you should avoid file names that differ only in case (e.g., makefile
and Makefile). Nowadays it is no longer worth worrying about the 8.3 limits of DOS file
systems.
Chapter 27: Frequently Asked Questions about Automake 120
27.5 Files left in build directory after distclean
This is a diagnostic you might encounter while running ‘make distcheck’.
As explained in Chapter 14 [Dist], page 93, ‘make distcheck’ attempts to build and
check your package for errors like this one.
‘make distcheck’ will perform a VPATH build of your package (see Section 2.2.6 [VPATH
Builds], page 6), and then call ‘make distclean’. Files left in the build directory after ‘make
distclean’ has run are listed after this error.
This diagnostic really covers two kinds of errors:
• files that are forgotten by distclean;
• distributed files that are erroneously rebuilt.
The former left-over files are not distributed, so the fix is to mark them for cleaning (see
Chapter 13 [Clean], page 93), this is obvious and doesn’t deserve more explanations.
The latter bug is not always easy to understand and fix, so let’s proceed with an example.
Suppose our package contains a program for which we want to build a man page using
help2man. GNU help2man produces simple manual pages from the --help and --version
output of other commands (see Section “Overview” in The Help2man Manual). Because
we don’t to force want our users to install help2man, we decide to distribute the generated
man page using the following setup.
# This Makefile.am is bogus.
bin_PROGRAMS = foo
foo_SOURCES = foo.c
dist_man_MANS = foo.1
foo.1: foo$(EXEEXT)
help2man --output=foo.1 ./foo$(EXEEXT)
This will effectively distribute the man page. However, ‘make distcheck’ will fail with:
ERROR: files left in build directory after distclean:
./foo.1
Why was foo.1 rebuilt? Because although distributed, foo.1 depends on a non-
distributed built file: foo$(EXEEXT). foo$(EXEEXT) is built by the user, so it will always
appear to be newer than the distributed foo.1.
‘make distcheck’ caught an inconsistency in our package. Our intent was to distribute
foo.1 so users do not need installing help2man, however since this our rule causes this file
to be always rebuilt, users do need help2man. Either we should ensure that foo.1 is not
rebuilt by users, or there is no point in distributing foo.1.
More generally, the rule is that distributed files should never depend on non-distributed
built files. If you distribute something generated, distribute its sources.
One way to fix the above example, while still distributing foo.1 is to not depend on
foo$(EXEEXT). For instance, assuming foo --version and foo --help do not change
unless foo.c or configure.ac change, we could write the following Makefile.am:
bin_PROGRAMS = foo
foo_SOURCES = foo.c
dist_man_MANS = foo.1
Chapter 27: Frequently Asked Questions about Automake 121
foo.1: foo.c $(top_srcdir)/configure.ac
$(MAKE) $(AM_MAKEFLAGS) foo$(EXEEXT)
help2man --output=foo.1 ./foo$(EXEEXT)
This way, foo.1 will not get rebuilt every time foo$(EXEEXT) changes. The make call
makes sure foo$(EXEEXT) is up-to-date before help2man. Another way to ensure this would
be to use separate directories for binaries and man pages, and set SUBDIRS so that binaries
are built before man pages.
We could also decide not to distribute foo.1. In this case it’s fine to have foo.1
dependent upon foo$(EXEEXT), since both will have to be rebuilt. However it would be
impossible to build the package in a cross-compilation, because building foo.1 involves an
execution of foo$(EXEEXT).
Another context where such errors are common is when distributed files are built by
tools that are built by the package. The pattern is similar:
distributed-file: built-tools distributed-sources
build-command
should be changed to
distributed-file: distributed-sources
$(MAKE) $(AM_MAKEFLAGS) built-tools
build-command
or you could choose not to distribute distributed-file, if cross-compilation does not
matter.
The points made through these examples are worth a summary:
• Distributed files should never depend upon non-distributed built files.
• Distributed files should be distributed with all their dependencies.
• If a file is intended to be rebuilt by users, then there is no point in distributing it.
For desperate cases, it’s always possible to disable this check by setting distcleancheck_
listfiles as documented in Chapter 14 [Dist], page 93. Make sure you do understand the
reason why ‘make distcheck’ complains before you do this. distcleancheck_listfiles
is a way to hide errors, not to fix them. You can always do better.
27.6 Flag Variables Ordering
What is the difference between AM_CFLAGS, CFLAGS, and
mumble_CFLAGS?
Why does automake output CPPFLAGS after
AM_CPPFLAGS on compile lines? Shouldn’t it be the converse?
My configure adds some warning flags into CXXFLAGS. In
one Makefile.am I would like to append a new flag, however if I
put the flag into AM_CXXFLAGS it is prepended to the other
flags, not appended.
Chapter 27: Frequently Asked Questions about Automake 122
27.6.1 Compile Flag Variables
This section attempts to answer all the above questions. We will mostly discuss CPPFLAGS
in our examples, but actually the answer holds for all the compile flags used in Automake:
CCASFLAGS, CFLAGS, CPPFLAGS, CXXFLAGS, FCFLAGS, FFLAGS, GCJFLAGS, LDFLAGS, LFLAGS,
LIBTOOLFLAGS, OBJCFLAGS, RFLAGS, UPCFLAGS, and YFLAGS.
CPPFLAGS, AM_CPPFLAGS, and mumble_CPPFLAGS are three variables that can be used to
pass flags to the C preprocessor (actually these variables are also used for other languages
like C++ or preprocessed Fortran). CPPFLAGS is the user variable (see Section 3.5 [User
Variables], page 21), AM_CPPFLAGS is the Automake variable, and mumble_CPPFLAGS is the
variable specific to the mumble target (we call this a per-target variable, see Section 8.4
[Program and Library Variables], page 62).
Automake always uses two of these variables when compiling C sources files. When
compiling an object file for the mumble target, the first variable will be mumble_CPPFLAGS
if it is defined, or AM_CPPFLAGS otherwise. The second variable is always CPPFLAGS.
In the following example,
bin_PROGRAMS = foo bar
foo_SOURCES = xyz.c
bar_SOURCES = main.c
foo_CPPFLAGS = -DFOO
AM_CPPFLAGS = -DBAZ
xyz.o will be compiled with ‘$(foo_CPPFLAGS) $(CPPFLAGS)’, (because xyz.o is part of the
foo target), while main.o will be compiled with ‘$(AM_CPPFLAGS) $(CPPFLAGS)’ (because
there is no per-target variable for target bar).
The difference between mumble_CPPFLAGS and AM_CPPFLAGS being clear enough, let’s
focus on CPPFLAGS. CPPFLAGS is a user variable, i.e., a variable that users are entitled to
modify in order to compile the package. This variable, like many others, is documented at
the end of the output of ‘configure --help’.
For instance, someone who needs to add /home/my/usr/include to the C compiler’s
search path would configure a package with
./configure CPPFLAGS=’-I /home/my/usr/include’
and this flag would be propagated to the compile rules of all Makefiles.
It is also not uncommon to override a user variable at make-time. Many installers do
this with prefix, but this can be useful with compiler flags too. For instance, if, while
debugging a C++ project, you need to disable optimization in one specific object file, you
can run something like
rm file.o
make CXXFLAGS=-O0 file.o
make
The reason ‘$(CPPFLAGS)’ appears after ‘$(AM_CPPFLAGS)’ or ‘$(mumble_CPPFLAGS)’ in
the compile command is that users should always have the last say. It probably makes
more sense if you think about it while looking at the ‘CXXFLAGS=-O0’ above, which should
supersede any other switch from AM_CXXFLAGS or mumble_CXXFLAGS (and this of course
replaces the previous value of CXXFLAGS).
Chapter 27: Frequently Asked Questions about Automake 123
You should never redefine a user variable such as CPPFLAGS in Makefile.am. Use
‘automake -Woverride’ to diagnose such mistakes. Even something like
CPPFLAGS = -DDATADIR=\"$(datadir)\" @CPPFLAGS@
is erroneous. Although this preserves configure’s value of CPPFLAGS, the definition of
DATADIR will disappear if a user attempts to override CPPFLAGS from the make command
line.
AM_CPPFLAGS = -DDATADIR=\"$(datadir)\"
is all what is needed here if no per-target flags are used.
You should not add options to these user variables within configure either, for the same
reason. Occasionally you need to modify these variables to perform a test, but you should
reset their values afterwards. In contrast, it is OK to modify the ‘AM_’ variables within
configure if you AC_SUBST them, but it is rather rare that you need to do this, unless you
really want to change the default definitions of the ‘AM_’ variables in all Makefiles.
What we recommend is that you define extra flags in separate variables. For instance, you
may write an Autoconf macro that computes a set of warning options for the C compiler, and
AC_SUBST them in WARNINGCFLAGS; you may also have an Autoconf macro that determines
which compiler and which linker flags should be used to link with library libfoo, and AC_
SUBST these in LIBFOOCFLAGS and LIBFOOLDFLAGS. Then, a Makefile.am could use these
variables as follows:
AM_CFLAGS = $(WARNINGCFLAGS)
bin_PROGRAMS = prog1 prog2
prog1_SOURCES = ...
prog2_SOURCES = ...
prog2_CFLAGS = $(LIBFOOCFLAGS) $(AM_CFLAGS)
prog2_LDFLAGS = $(LIBFOOLDFLAGS)
In this example both programs will be compiled with the flags substituted into
‘$(WARNINGCFLAGS)’, and prog2 will additionally be compiled with the flags required to
link with libfoo.
Note that listing AM_CFLAGS in a per-target CFLAGS variable is a common idiom to ensure
that AM_CFLAGS applies to every target in a Makefile.in.
Using variables like this gives you full control over the ordering of the flags. For instance,
if there is a flag in $(WARNINGCFLAGS) that you want to negate for a particular target,
you can use something like ‘prog1_CFLAGS = $(AM_CFLAGS) -no-flag’. If all these flags
had been forcefully appended to CFLAGS, there would be no way to disable one flag. Yet
another reason to leave user variables to users.
Finally, we have avoided naming the variable of the example LIBFOO_LDFLAGS (with an
underscore) because that would cause Automake to think that this is actually a per-target
variable (like mumble_LDFLAGS) for some non-declared LIBFOO target.
27.6.2 Other Variables
There are other variables in Automake that follow similar principles to allow user options.
For instance, Texinfo rules (see Section 11.1 [Texinfo], page 88) use MAKEINFOFLAGS
and AM_MAKEINFOFLAGS. Similarly, DejaGnu tests (see Chapter 15 [Tests], page 97)
use RUNTESTDEFAULTFLAGS and AM_RUNTESTDEFAULTFLAGS. The tags and ctags rules
Chapter 27: Frequently Asked Questions about Automake 124
(see Section 18.1 [Tags], page 103) use ETAGSFLAGS, AM_ETAGSFLAGS, CTAGSFLAGS, and
AM_CTAGSFLAGS. Java rules (see Section 10.4 [Java], page 85) use JAVACFLAGS and
AM_JAVACFLAGS. None of these rules supports per-target flags (yet).
To some extent, even AM_MAKEFLAGS (see Section 7.1 [Subdirectories], page 45) obeys this
naming scheme. The slight difference is that MAKEFLAGS is passed to sub-makes implicitly
by make itself.
However you should not think that all variables ending with FLAGS follow this convention.
For instance, DISTCHECK_CONFIGURE_FLAGS (see Chapter 14 [Dist], page 93), ACLOCAL_
AMFLAGS (see Chapter 16 [Rebuilding], page 98, and Section 6.3.4 [Local Macros], page 38),
are two variables that are only useful to the maintainer and have no user counterpart.
ARFLAGS (see Section 8.2 [A Library], page 55) is usually defined by Automake and has
neither AM_ nor per-target cousin.
Finally you should not think either that the existence of a per-target variable implies that
of an AM_ variable or that of a user variable. For instance, the mumble_LDADD per-target
variable overrides the global LDADD variable (which is not a user variable), and mumble_
LIBADD exists only as a per-target variable. See Section 8.4 [Program and Library Variables],
page 62.
27.7 Why are object files sometimes renamed?
This happens when per-target compilation flags are used. Object files need to be renamed
just in case they would clash with object files compiled from the same sources, but with
different flags. Consider the following example.
bin_PROGRAMS = true false
true_SOURCES = generic.c
true_CPPFLAGS = -DEXIT_CODE=0
false_SOURCES = generic.c
false_CPPFLAGS = -DEXIT_CODE=1
Obviously the two programs are built from the same source, but it would be bad if they
shared the same object, because generic.o cannot be built with both ‘-DEXIT_CODE=0’
and ‘-DEXIT_CODE=1’. Therefore automake outputs rules to build two different objects:
true-generic.o and false-generic.o.
automake doesn’t actually look whether source files are shared to decide if it must rename
objects. It will just rename all objects of a target as soon as it sees per-target compilation
flags are used.
It’s OK to share object files when per-target compilation flags are not used. For instance,
true and false will both use version.o in the following example.
AM_CPPFLAGS = -DVERSION=1.0
bin_PROGRAMS = true false
true_SOURCES = true.c version.c
false_SOURCES = false.c version.c
Note that the renaming of objects is also affected by the _SHORTNAME variable (see
Section 8.4 [Program and Library Variables], page 62).
Chapter 27: Frequently Asked Questions about Automake 125
27.8 Per-Object Flags Emulation
One of my source files needs to be compiled with different flags. How
do I do?
Automake supports per-program and per-library compilation flags (see Section 8.4 [Pro-
gram and Library Variables], page 62, and Section 27.6 [Flag Variables Ordering], page 121).
With this you can define compilation flags that apply to all files compiled for a target. For
instance, in
bin_PROGRAMS = foo
foo_SOURCES = foo.c foo.h bar.c bar.h main.c
foo_CFLAGS = -some -flags
foo-foo.o, foo-bar.o, and foo-main.o will all be compiled with ‘-some -flags’. (If you
wonder about the names of these object files, see Section 27.7 [renamed objects], page 124.)
Note that foo_CFLAGS gives the flags to use when compiling all the C sources of the program
foo, it has nothing to do with foo.c or foo-foo.o specifically.
What if foo.c needs to be compiled into foo.o using some specific flags, that none
of the other files requires? Obviously per-program flags are not directly applicable here.
Something like per-object flags are expected, i.e., flags that would be used only when cre-
ating foo-foo.o. Automake does not support that, however this is easy to simulate using
a library that contains only that object, and compiling this library with per-library flags.
bin_PROGRAMS = foo
foo_SOURCES = bar.c bar.h main.c
foo_CFLAGS = -some -flags
foo_LDADD = libfoo.a
noinst_LIBRARIES = libfoo.a
libfoo_a_SOURCES = foo.c foo.h
libfoo_a_CFLAGS = -some -other -flags
Here foo-bar.o and foo-main.o will all be compiled with ‘-some -flags’, while
libfoo_a-foo.o will be compiled using ‘-some -other -flags’. Eventually, all three
objects will be linked to form foo.
This trick can also be achieved using Libtool convenience libraries, for instance
‘noinst_LTLIBRARIES = libfoo.la’ (see Section 8.3.5 [Libtool Convenience Libraries],
page 58).
Another tempting idea to implement per-object flags is to override the compile rules
automake would output for these files. Automake will not define a rule for a target you
have defined, so you could think about defining the ‘foo-foo.o: foo.c’ rule yourself. We
recommend against this, because this is error prone. For instance, if you add such a rule to
the first example, it will break the day you decide to remove foo_CFLAGS (because foo.c
will then be compiled as foo.o instead of foo-foo.o, see Section 27.7 [renamed objects],
page 124). Also in order to support dependency tracking, the two .o/.obj extensions, and
all the other flags variables involved in a compilation, you will end up modifying a copy of
the rule previously output by automake for this file. If a new release of Automake generates
a different rule, your copy will need to be updated by hand.
Chapter 27: Frequently Asked Questions about Automake 126
27.9 Handling Tools that Produce Many Outputs
This section describes a make idiom that can be used when a tool produces multiple output
files. It is not specific to Automake and can be used in ordinary Makefiles.
Suppose we have a program called foo that will read one file called data.foo and produce
two files named data.c and data.h. We want to write a Makefile rule that captures this
one-to-two dependency.
The naive rule is incorrect:
# This is incorrect.
data.c data.h: data.foo
foo data.foo
What the above rule really says is that data.c and data.h each depend on data.foo, and
can each be built by running ‘foo data.foo’. In other words it is equivalent to:
# We do not want this.
data.c: data.foo
foo data.foo
data.h: data.foo
foo data.foo
which means that foo can be run twice. Usually it will not be run twice, because make
implementations are smart enough to check for the existence of the second file after the
first one has been built; they will therefore detect that it already exists. However there are
a few situations where it can run twice anyway:
• The most worrying case is when running a parallel make. If data.c and data.h are
built in parallel, two ‘foo data.foo’ commands will run concurrently. This is harmful.
• Another case is when the dependency (here data.foo) is (or depends upon) a phony
target.
A solution that works with parallel make but not with phony dependencies is the follow-
ing:
data.c data.h: data.foo
foo data.foo
data.h: data.c
The above rules are equivalent to
data.c: data.foo
foo data.foo
data.h: data.foo data.c
foo data.foo
therefore a parallel make will have to serialize the builds of data.c and data.h, and will
detect that the second is no longer needed once the first is over.
Using this pattern is probably enough for most cases. However it does not scale easily to
more output files (in this scheme all output files must be totally ordered by the dependency
relation), so we will explore a more complicated solution.
Another idea is to write the following:
# There is still a problem with this one.
data.c: data.foo
Chapter 27: Frequently Asked Questions about Automake 127
foo data.foo
data.h: data.c
The idea is that ‘foo data.foo’ is run only when data.c needs to be updated, but we
further state that data.h depends upon data.c. That way, if data.h is required and
data.foo is out of date, the dependency on data.c will trigger the build.
This is almost perfect, but suppose we have built data.h and data.c, and then we erase
data.h. Then, running ‘make data.h’ will not rebuild data.h. The above rules just state
that data.c must be up-to-date with respect to data.foo, and this is already the case.
What we need is a rule that forces a rebuild when data.h is missing. Here it is:
data.c: data.foo
foo data.foo
data.h: data.c
## Recover from the removal of $@
@if test -f $@; then :; else \
rm -f data.c; \
$(MAKE) $(AM_MAKEFLAGS) data.c; \
fi
The above scheme can be extended to handle more outputs and more inputs. One of the
outputs is selected to serve as a witness to the successful completion of the command, it
depends upon all inputs, and all other outputs depend upon it. For instance, if foo should
additionally read data.bar and also produce data.w and data.x, we would write:
data.c: data.foo data.bar
foo data.foo data.bar
data.h data.w data.x: data.c
## Recover from the removal of $@
@if test -f $@; then :; else \
rm -f data.c; \
$(MAKE) $(AM_MAKEFLAGS) data.c; \
fi
However there are now two minor problems in this setup. One is related to the timestamp
ordering of data.h, data.w, data.x, and data.c. The other one is a race condition if a
parallel make attempts to run multiple instances of the recover block at once.
Let us deal with the first problem. foo outputs four files, but we do not know in which
order these files are created. Suppose that data.h is created before data.c. Then we have
a weird situation. The next time make is run, data.h will appear older than data.c, the
second rule will be triggered, a shell will be started to execute the ‘if...fi’ command, but
actually it will just execute the then branch, that is: nothing. In other words, because the
witness we selected is not the first file created by foo, make will start a shell to do nothing
each time it is run.
A simple riposte is to fix the timestamps when this happens.
data.c: data.foo data.bar
foo data.foo data.bar
data.h data.w data.x: data.c
@if test -f $@; then \
touch $@; \
Chapter 27: Frequently Asked Questions about Automake 128
else \
## Recover from the removal of $@
rm -f data.c; \
$(MAKE) $(AM_MAKEFLAGS) data.c; \
fi
Another solution is to use a different and dedicated file as witness, rather than using
any of foo’s outputs.
data.stamp: data.foo data.bar
@rm -f data.tmp
@touch data.tmp
foo data.foo data.bar
@mv -f data.tmp $@
data.c data.h data.w data.x: data.stamp
## Recover from the removal of $@
@if test -f $@; then :; else \
rm -f data.stamp; \
$(MAKE) $(AM_MAKEFLAGS) data.stamp; \
fi
data.tmp is created before foo is run, so it has a timestamp older than output files
output by foo. It is then renamed to data.stamp after foo has run, because we do not
want to update data.stamp if foo fails.
This solution still suffers from the second problem: the race condition in the recover rule.
If, after a successful build, a user erases data.c and data.h, and runs ‘make -j’, then make
may start both recover rules in parallel. If the two instances of the rule execute ‘$(MAKE)
$(AM_MAKEFLAGS) data.stamp’ concurrently the build is likely to fail (for instance, the two
rules will create data.tmp, but only one can rename it).
Admittedly, such a weird situation does not arise during ordinary builds. It occurs only
when the build tree is mutilated. Here data.c and data.h have been explicitly removed
without also removing data.stamp and the other output files. make clean; make will always
recover from these situations even with parallel makes, so you may decide that the recover
rule is solely to help non-parallel make users and leave things as-is. Fixing this requires some
locking mechanism to ensure only one instance of the recover rule rebuilds data.stamp. One
could imagine something along the following lines.
data.c data.h data.w data.x: data.stamp
## Recover from the removal of $@
@if test -f $@; then :; else \
trap ’rm -rf data.lock data.stamp’ 1 2 13 15; \
## mkdir is a portable test-and-set
if mkdir data.lock 2>/dev/null; then \
## This code is being executed by the first process.
rm -f data.stamp; \
$(MAKE) $(AM_MAKEFLAGS) data.stamp; \
result=$$?; rm -rf data.lock; exit $$result; \
else \
## This code is being executed by the follower processes.
Chapter 27: Frequently Asked Questions about Automake 129
## Wait until the first process is done.
while test -d data.lock; do sleep 1; done; \
## Succeed if and only if the first process succeeded.
test -f data.stamp; \
fi; \
fi
Using a dedicated witness, like data.stamp, is very handy when the list of output files
is not known beforehand. As an illustration, consider the following rules to compile many
*.el files into *.elc files in a single command. It does not matter how ELFILES is defined
(as long as it is not empty: empty targets are not accepted by POSIX).
ELFILES = one.el two.el three.el ...
ELCFILES = $(ELFILES:=c)
elc-stamp: $(ELFILES)
@rm -f elc-temp
@touch elc-temp
$(elisp_comp) $(ELFILES)
@mv -f elc-temp $@
$(ELCFILES): elc-stamp
## Recover from the removal of $@
@if test -f $@; then :; else \
trap ’rm -rf elc-lock elc-stamp’ 1 2 13 15; \
if mkdir elc-lock 2>/dev/null; then \
## This code is being executed by the first process.
rm -f elc-stamp; \
$(MAKE) $(AM_MAKEFLAGS) elc-stamp; \
rmdir elc-lock; \
else \
## This code is being executed by the follower processes.
## Wait until the first process is done.
while test -d elc-lock; do sleep 1; done; \
## Succeed if and only if the first process succeeded.
test -f elc-stamp; exit $$?; \
fi; \
fi
For completeness it should be noted that GNU make is able to express rules with multiple
output files using pattern rules (see Section “Pattern Rule Examples” in The GNU Make
Manual). We do not discuss pattern rules here because they are not portable, but they can
be convenient in packages that assume GNU make.
27.10 Installing to Hard-Coded Locations
My package needs to install some configuration file. I tried to use
the following rule, but ‘make distcheck’ fails. Why?
# Do not do this.
Chapter 27: Frequently Asked Questions about Automake 130
install-data-local:
$(INSTALL_DATA) $(srcdir)/afile $(DESTDIR)/etc/afile
My package needs to populate the installation directory of another
package at install-time. I can easily compute that installation
directory in configure, but if I install files therein,
‘make distcheck’ fails. How else should I do?
These two setups share their symptoms: ‘make distcheck’ fails because they are in-
stalling files to hard-coded paths. In the later case the path is not really hard-coded in
the package, but we can consider it to be hard-coded in the system (or in whichever tool
that supplies the path). As long as the path does not use any of the standard directory
variables (‘$(prefix)’, ‘$(bindir)’, ‘$(datadir)’, etc.), the effect will be the same: user-
installations are impossible.
When a (non-root) user wants to install a package, he usually has no right to install
anything in /usr or /usr/local. So he does something like ‘./configure --prefix ~/usr’
to install package in his own ~/usr tree.
If a package attempts to install something to some hard-coded path (e.g., /etc/afile),
regardless of this --prefix setting, then the installation will fail. ‘make distcheck’ per-
forms such a --prefix installation, hence it will fail too.
Now, there are some easy solutions.
The above install-data-local example for installing /etc/afile would be better
replaced by
sysconf_DATA = afile
by default sysconfdir will be ‘$(prefix)/etc’, because this is what the GNU Standards
require. When such a package is installed on a FHS compliant system, the installer will
have to set ‘--sysconfdir=/etc’. As the maintainer of the package you should not be
concerned by such site policies: use the appropriate standard directory variable to install
your files so that installer can easily redefine these variables to match their site conventions.
Installing files that should be used by another package is slightly more involved. Let’s
take an example and assume you want to install shared library that is a Python extension
module. If you ask Python where to install the library, it will answer something like this:
% python -c ’from distutils import sysconfig;
print sysconfig.get_python_lib(1,0)’
/usr/lib/python2.3/site-packages
If you indeed use this absolute path to install your shared library, non-root users will
not be able to install the package, hence distcheck fails.
Let’s do better. The ‘sysconfig.get_python_lib()’ function actually accepts a third
argument that will replace Python’s installation prefix.
% python -c ’from distutils import sysconfig;
print sysconfig.get_python_lib(1,0,"${exec_prefix}")’
${exec_prefix}/lib/python2.3/site-packages
You can also use this new path. If you do
• root users can install your package with the same --prefix as Python (you get the
behavior of the previous attempt)
Chapter 28: History of Automake 131
• non-root users can install your package too, they will have the extension module in a
place that is not searched by Python but they can work around this using environment
variables (and if you installed scripts that use this shared library, it’s easy to tell Python
were to look in the beginning of your script, so the script works in both cases).
The AM_PATH_PYTHON macro uses similar commands to define ‘$(pythondir)’ and
‘$(pyexecdir)’ (see Section 10.5 [Python], page 86).
Of course not all tools are as advanced as Python regarding that substitution of prefix.
So another strategy is to figure the part of the of the installation directory that must be
preserved. For instance, here is how AM_PATH_LISPDIR (see Section 10.1 [Emacs Lisp],
page 84) computes ‘$(lispdir)’:
$EMACS -batch -q -eval ’(while load-path
(princ (concat (car load-path) "\n"))
(setq load-path (cdr load-path)))’ >conftest.out
lispdir=‘sed -n
-e ’s,/$,,’
-e ’/.*\/lib\/x*emacs\/site-lisp$/{
s,.*/lib/\(x*emacs/site-lisp\)$,${libdir}/\1,;p;q;
}’
-e ’/.*\/share\/x*emacs\/site-lisp$/{
s,.*/share/\(x*emacs/site-lisp\),${datarootdir}/\1,;p;q;
}’
conftest.out‘
I.e., it just picks the first directory that looks like */lib/*emacs/site-lisp or
*/share/*emacs/site-lisp in the search path of emacs, and then substitutes ‘${libdir}’
or ‘${datadir}’ appropriately.
The emacs case looks complicated because it processes a list and expect two possible
layouts, otherwise it’s easy, and the benefit for non-root users are really worth the extra
sed invocation.
28 History of Automake
This chapter presents various aspects of the history of Automake. The exhausted reader
can safely skip it; this will be more of interest to nostalgic people, or to those curious to
learn about the evolution of Automake.
28.1 Timeline
1994-09-19 First CVS commit.
If we can trust the CVS repository, David J. MacKenzie (djm) started working
on Automake (or AutoMake, as it was spelt then) this Monday.
The first version of the automake script looks as follows.
#!/bin/sh
status=0
Chapter 28: History of Automake 132
for makefile
do
if test ! -f ${makefile}.am; then
echo "automake: ${makefile}.am: No such honkin’ file"
status=1
continue
fi
exec 4> ${makefile}.in
done
From this you can already see that Automake will be about reading *.am file
and producing *.in files. You cannot see anything else, but if you also know
that David is the one who created Autoconf two years before you can guess the
rest.
Several commits follow, and by the end of the day Automake is reported to
work for GNU fileutils and GNU m4.
The modus operandi is the one that is still used today: variable assignments in
Makefile.am files trigger injections of precanned Makefile fragments into the
generated Makefile.in. The use of Makefile fragments was inspired by the
4.4BSD make and include files, however Automake aims to be portable and to
conform to the GNU standards for Makefile variables and targets.
At this point, the most recent release of Autoconf is version 1.11, and David is
preparing to release Autoconf 2.0 in late October. As a matter of fact, he will
barely touch Automake after September.
1994-11-05 David MacKenzie’s last commit.
At this point Automake is a 200 line portable shell script, plus 332 lines of
Makefile fragments. In the README, David states his ambivalence between
“portable shell” and “more appropriate language”:
I wrote it keeping in mind the possibility of it becoming an Au-
toconf macro, so it would run at configure-time. That would slow
configuration down a bit, but allow users to modify the Makefile.am
without needing to fetch the AutoMake package. And, the Make-
file.in files wouldn’t need to be distributed. But all of AutoMake
would. So I might reimplement AutoMake in Perl, m4, or some
other more appropriate language.
Automake is described as “an experimental Makefile generator”. There is no
documentation. Adventurous users are referred to the examples and patches
needed to use Automake with GNU m4 1.3, fileutils 3.9, time 1.6, and develop-
ment versions of find and indent.
These examples seem to have been lost. However at the time of writing (10
years later in September, 2004) the FSF still distributes a package that uses
this version of Automake: check out GNU termutils 2.0.
Chapter 28: History of Automake 133
1995-11-12 Tom Tromey’s first commit.
After one year of inactivity, Tom Tromey takes over the package. Tom was
working on GNU cpio back then, and doing this just for fun, having trouble
finding a project to contribute to. So while hacking he wanted to bring the
Makefile.in up to GNU standards. This was hard, and one day he saw Au-
tomake on ftp://alpha.gnu.org/, grabbed it and tried it out.
Tom didn’t talk to djm about it until later, just to make sure he didn’t mind if
he made a release. He did a bunch of early releases to the Gnits folks.
Gnits was (and still is) totally informal, just a few GNU friends who François
Pinard knew, who were all interested in making a common infrastructure for
GNU projects, and shared a similar outlook on how to do it. So they were able
to make some progress. It came along with Autoconf and extensions thereof,
and then Automake from David and Tom (who were both gnitsians). One of
their ideas was to write a document paralleling the GNU standards, that was
more strict in some ways and more detailed. They never finished the GNITS
standards, but the ideas mostly made their way into Automake.
1995-11-23 Automake 0.20
Besides introducing automatic dependency tracking (see Section 28.2 [Depen-
dency Tracking Evolution], page 143), this version also supplies a 9-page man-
ual.
At this time aclocal and AM_INIT_AUTOMAKE did not exist, so many things
had to be done by hand. For instance, here is what a configure.in (this is the
former name of the configure.ac we use today) must contain in order to use
Automake 0.20:
PACKAGE=cpio
VERSION=2.3.911
AC_DEFINE_UNQUOTED(PACKAGE, "$PACKAGE")
AC_DEFINE_UNQUOTED(VERSION, "$VERSION")
AC_SUBST(PACKAGE)
AC_SUBST(VERSION)
AC_ARG_PROGRAM
AC_PROG_INSTALL
(Today all of the above is achieved by AC_INIT and AM_INIT_AUTOMAKE.)
Here is how programs are specified in Makefile.am:
PROGRAMS = hello
hello_SOURCES = hello.c
This looks pretty much like what we do today, except the PROGRAMS variable has
no directory prefix specifying where hello should be installed: all programs are
installed in ‘$(bindir)’. LIBPROGRAMS can be used to specify programs that
must be built but not installed (it is called noinst_PROGRAMS nowadays).
Programs can be built conditionally using AC_SUBSTitutions:
PROGRAMS = @progs@
AM_PROGRAMS = foo bar baz
(AM_PROGRAMS has since then been renamed to EXTRA_PROGRAMS.)
Chapter 28: History of Automake 134
Similarly scripts, static libraries, and data can built and installed using the
LIBRARIES, SCRIPTS, and DATA variables. However LIBRARIES were treated a
bit specially in that Automake did automatically supply the lib and .a prefixes.
Therefore to build libcpio.a, one had to write
LIBRARIES = cpio
cpio_SOURCES = ...
Extra files to distribute must be listed in DIST_OTHER (the ancestor of EXTRA_
DIST). Also extra directories that are to be distributed should appear in DIST_
SUBDIRS, but the manual describes this as a temporary ugly hack (today extra
directories should also be listed in EXTRA_DIST, and DIST_SUBDIRS is used for
another purpose, see Section 7.2 [Conditional Subdirectories], page 46).
1995-11-26 Automake 0.21
In less time that it takes to cook a frozen pizza, Tom rewrites Automake using
Perl. At this time Perl 5 is only one year old, and Perl 4.036 is in use at many
sites. Supporting several Perl versions has been a source of problems through
the whole history of Automake.
If you never used Perl 4, imagine Perl 5 without objects, without ‘my’ variables
(only dynamically scoped ‘local’ variables), without function prototypes, with
function calls that needs to be prefixed with ‘&’, etc. Traces of this old style
can still be found in today’s automake.
1995-11-28 Automake 0.22
1995-11-29 Automake 0.23
Bug fixes.
1995-12-08 Automake 0.24
1995-12-10 Automake 0.25
Releases are raining. 0.24 introduces the uniform naming scheme we use
today, i.e., bin_PROGRAMS instead of PROGRAMS, noinst_LIBRARIES instead
of LIBLIBRARIES, etc. (However EXTRA_PROGRAMS does not exist yet,
AM_PROGRAMS is still in use; and TEXINFOS and MANS still have no directory
prefixes.) Adding support for prefixes like that was one of the major ideas in
automake; it has lasted pretty well.
AutoMake is renamed to Automake (Tom seems to recall it was François
Pinard’s doing).
0.25 fixes a Perl 4 portability bug.
1995-12-18 Jim Meyering starts using Automake in GNU Textutils.
1995-12-31 François Pinard starts using Automake in GNU tar.
1996-01-03 Automake 0.26
1996-01-03 Automake 0.27
Of the many changes and suggestions sent by François Pinard and included
in 0.26, perhaps the most important is the advice that to ease customization
a user rule or variable definition should always override an Automake rule or
definition.
Gordon Matzigkeit and Jim Meyering are two other early contributors that
have been sending fixes.
Chapter 28: History of Automake 135
0.27 fixes yet another Perl 4 portability bug.
1996-01-13 Automake 0.28
Automake starts scanning configure.in for LIBOBJS support. This is an
important step because until this version Automake only knew about the
Makefile.ams it processed. configure.in was Autoconf’s world and the
link between Autoconf and Automake had to be done by the Makefile.am
author. For instance, if config.h was generated by configure, it was the
package maintainer’s responsibility to define the CONFIG_HEADER variable in
each Makefile.am.
Succeeding releases will rely more and more on scanning configure.in to bet-
ter automate the Autoconf integration.
0.28 also introduces the AUTOMAKE_OPTIONS variable and the --gnu and --gnits
options, the latter being stricter.
1996-02-07 Automake 0.29
Thanks to configure.in scanning, CONFIG_HEADER is gone, and rebuild rules
for configure-generated file are automatically output.
TEXINFOS and MANS converted to the uniform naming scheme.
1996-02-24 Automake 0.30
The test suite is born. It contains 9 tests. From now on test cases will be added
pretty regularly (see Section 28.3 [Releases], page 147), and this proved to be
really helpful later on.
EXTRA_PROGRAMS finally replaces AM_PROGRAMS.
All the third-party Autoconf macros, written mostly by François Pinard (and
later Jim Meyering), are distributed in Automake’s hand-written aclocal.m4
file. Package maintainers are expected to extract the necessary macros from this
file. (In previous version you had to copy and paste them from the manual...)
1996-03-11 Automake 0.31
The test suite in 0.30 was run via a long check-local rule. Upon Ulrich
Drepper’s suggestion, 0.31 makes it an Automake rule output whenever the
TESTS variable is defined.
DIST_OTHER is renamed to EXTRA_DIST, and the check_ prefix is introduced.
The syntax is now the same as today.
1996-03-15 Gordon Matzigkeit starts writing libtool.
1996-04-27 Automake 0.32
-hook targets are introduced; an idea from Dieter Baron.
*.info files, which were output in the build directory are now built in the
source directory, because they are distributed. It seems these files like to move
back and forth as that will happen again in future versions.
1996-05-18 Automake 0.33
Gord Matzigkeit’s main two contributions:
• very preliminary libtool support
• the distcheck rule
Chapter 28: History of Automake 136
Although they were very basic at this point, these are probably among the top
features for Automake today.
Jim Meyering also provides the infamous jm_MAINTAINER_MODE, since then re-
named to AM_MAINTAINER_MODE and abandoned by its author (see Section 27.2
[maintainer-mode], page 117).
1996-05-28 Automake 1.0
After only six months of heavy development, the automake script is 3134 lines
long, plus 973 lines of Makefile fragments. The package has 30 pages of docu-
mentation, and 38 test cases. aclocal.m4 contains 4 macros.
From now on and until version 1.4, new releases will occur at a rate of about
one a year. 1.1 did not exist, actually 1.1b to 1.1p have been the name of beta
releases for 1.2. This is the first time Automake uses suffix letters to designate
beta releases, an habit that lasts.
1996-10-10 Kevin Dalley packages Automake 1.0 for Debian GNU/Linux.
1996-11-26 David J. MacKenzie releases Autoconf 2.12.
Between June and October, the Autoconf development is almost stalled. Roland
McGrath has been working at the beginning of the year. David comes back in
November to release 2.12, but he won’t touch Autoconf anymore after this year,
and Autoconf then really stagnates. The desolate Autoconf ChangeLog for 1997
lists only 7 commits.
1997-02-28 automake@gnu.ai.mit.edu list alive
The mailing list is announced as follows:
I’ve created the "automake" mailing list. It is
"automake@gnu.ai.mit.edu". Administrivia, as always, to
automake-request@gnu.ai.mit.edu.
The charter of this list is discussion of automake, autoconf, and
other configuration/portability tools (e.g., libtool). It is expected
that discussion will range from pleas for help all the way up to
patches.
This list is archived on the FSF machines. Offhand I don’t know if
you can get the archive without an account there.
This list is open to anybody who wants to join. Tell all your
friends!
-- Tom Tromey
Before that people were discussing Automake privately, on the Gnits mailing
list (which is not public either), and less frequently on gnu.misc.discuss.
gnu.ai.mit.edu is now gnu.org, in case you never noticed. The archives of the
early years of the automake@gnu.org list have been lost, so today it is almost
impossible to find traces of discussions that occurred before 1999. This has
been annoying more than once, as such discussions can be useful to understand
the rationale behind a piece of uncommented code that was introduced back
then.
1997-06-22 Automake 1.2
Automake developments continues, and more and more new Autoconf macros
are required. Distributing them in aclocal.m4 and requiring people to browse
Chapter 28: History of Automake 137
this file to extract the relevant macros becomes uncomfortable. Ideally, some
of them should be contributed to Autoconf so that they can be used directly,
however Autoconf is currently inactive. Automake 1.2 consequently introduces
aclocal (aclocal was actually started on 1996-07-28), a tool that automat-
ically constructs an aclocal.m4 file from a repository of third-party macros.
Because Autoconf has stalled, Automake also becomes a kind of repository for
such third-party macros, even macros completely unrelated to Automake (for
instance macros that fix broken Autoconf macros).
The 1.2 release contains 20 macros, including the AM_INIT_AUTOMAKE macro
that simplifies the creation of configure.in.
Libtool is fully supported using *_LTLIBRARIES.
The missing script is introduced by François Pinard; it is meant to be a bet-
ter solution than AM_MAINTAINER_MODE (see Section 27.2 [maintainer-mode],
page 117).
Conditionals support was implemented by Ian Lance Taylor. At the time, Tom
and Ian were working on an internal project at Cygnus. They were using ILU,
which is pretty similar to CORBA. They wanted to integrate ILU into their
build, which was all configure-based, and Ian thought that adding conditionals
to automake was simpler than doing all the work in configure (which was the
standard at the time). So this was actually funded by Cygnus.
This very useful but tricky feature will take a lot of time to stabilize. (At the
time this text is written, there are still primaries that have not been updated
to support conditional definitions in Automake 1.9.)
The automake script has almost doubled: 6089 lines of Perl, plus 1294 lines of
Makefile fragments.
1997-07-08 Gordon Matzigkeit releases Libtool 1.0.
1998-04-05 Automake 1.3
This is a small advance compared to 1.2. It adds support for assembly, and
preliminary support for Java.
Perl 5.004 04 is out, but fixes to support Perl 4 are still regularly submitted
whenever Automake breaks it.
1998-09-06 sourceware.cygnus.com is on-line.
Sourceware was setup by Jason Molenda to host open source projects.
1998-09-19 Automake CVS repository moved to sourceware.cygnus.com
1998-10-26 sourceware.cygnus.com announces it hosts Automake:
Automake is now hosted on sourceware.cygnus.com. It has a publicly ac-
cessible CVS repository. This CVS repository is a copy of the one Tom was
using on his machine, which in turn is based on a copy of the CVS repos-
itory of David MacKenzie. This is why we still have to full source history.
(Automake was on Sourceware until 2007-10-29, when it moved to a git repos-
itory on savannah.gnu.org, but the Sourceware host had been renamed to
sources.redhat.com.)
The oldest file in the administrative directory of the CVS repository that
was created on Sourceware is dated 1998-09-19, while the announcement that
Chapter 28: History of Automake 138
automake and autoconf had joined sourceware was made on 1998-10-26. They
were among the first projects to be hosted there.
The heedful reader will have noticed Automake was exactly 4 years old on
1998-09-19.
1999-01-05 Ben Elliston releases Autoconf 2.13.
1999-01-14 Automake 1.4
This release adds support for Fortran 77 and for the include statement. Also,
‘+=’ assignments are introduced, but it is still quite easy to fool Automake when
mixing this with conditionals.
These two releases, Automake 1.4 and Autoconf 2.13 make a duo that will be
used together for years.
automake is 7228 lines, plus 1591 lines of Makefile fragment, 20 macros (some
1.3 macros were finally contributed back to Autoconf), 197 test cases, and 51
pages of documentation.
1999-03-27 The user-dep-branch is created on the CVS repository.
This implements a new dependency tracking schemed that should be able to
handle automatic dependency tracking using any compiler (not just gcc) and
any make (not just GNU make). In addition, the new scheme should be more
reliable than the old one, as dependencies are generated on the end user’s
machine. Alexandre Oliva creates depcomp for this purpose.
See Section 28.2 [Dependency Tracking Evolution], page 143, for more details
about the evolution of automatic dependency tracking in Automake.
1999-11-21 The user-dep-branch is merged into the main trunk.
This was a huge problem since we also had patches going in on the trunk. The
merge took a long time and was very painful.
2000-05-10
Since September 1999 and until 2003, Akim Demaille will be zealously revamp-
ing Autoconf.
I think the next release should be called "3.0".
Let’s face it: you’ve basically rewritten autoconf.
Every weekend there are 30 new patches.
I don’t see how we could call this "2.15" with a straight face.
– Tom Tromey on autoconf@gnu.org
Actually Akim works like a submarine: he will pile up patches while he works
off-line during the weekend, and flush them in batch when he resurfaces on
Monday.
2001-01-24
On this Wednesday, Autoconf 2.49c, the last beta before Autoconf 2.50 is out,
and Akim has to find something to do during his week-end :)
2001-01-28
Akim sends a batch of 14 patches to automake@gnu.org.
Aiieeee! I was dreading the day that the Demaillator turned his
sights on automake. . . and now it has arrived! – Tom Tromey
Chapter 28: History of Automake 139
It’s only the beginning: in two months he will send 192 patches. Then he would
slow down so Tom can catch up and review all this. Initially Tom actually read
all these patches, then he probably trustingly answered OK to most of them,
and finally gave up and let Akim apply whatever he wanted. There was no way
to keep up with that patch rate.
Anyway the patch below won’t apply since it predates Akim’s
sourcequake; I have yet to figure where the relevant passage has
been moved :) – Alexandre Duret-Lutz
All these patches were sent to and discussed on automake@gnu.org, so
subscribed users were literally drowning in technical mails. Eventually, the
automake-patches@gnu.org mailing list was created in May.
Year after year, Automake had drifted away from its initial design: construct
Makefile.in by assembling various Makefile fragments. In 1.4, lots of
Makefile rules are being emitted at various places in the automake script
itself; this does not help ensuring a consistent treatment of these rules
(for instance making sure that user-defined rules override Automake’s own
rules). One of Akim’s goal was moving all these hard-coded rules to separate
Makefile fragments, so the logic could be centralized in a Makefile fragment
processor.
Another significant contribution of Akim is the interface with the “trace” fea-
ture of Autoconf. The way to scan configure.in at this time was to read the
file and grep the various macro of interest to Automake. Doing so could break
in many unexpected ways; automake could miss some definition (for instance
‘AC_SUBST([$1], [$2])’ where the arguments are known only when M4 is run),
or conversely it could detect some macro that was not expanded (because it is
called conditionally). In the CVS version of Autoconf, Akim had implemented
the --trace option, which provides accurate information about where macros
are actually called and with what arguments. Akim will equip Automake with
a second configure.in scanner that uses this --trace interface. Since it was
not sensible to drop the Autoconf 2.13 compatibility yet, this experimental
scanner was only used when an environment variable was set, the traditional
grep-scanner being still the default.
2001-04-25 Gary V. Vaughan releases Libtool 1.4
It has been more than two years since Automake 1.4, CVS Automake has
suffered lot’s of heavy changes and still is not ready for release. Libtool 1.4
had to be distributed with a patch against Automake 1.4.
2001-05-08 Automake 1.4-p1
2001-05-24 Automake 1.4-p2
Gary V. Vaughan, the principal Libtool maintainer, makes a “patch release” of
Automake:
The main purpose of this release is to have a stable automake which
is compatible with the latest stable libtool.
The release also contains obvious fixes for bugs in Automake 1.4, some of which
were reported almost monthly.
Chapter 28: History of Automake 140
2001-05-21 Akim Demaille releases Autoconf 2.50
2001-06-07 Automake 1.4-p3
2001-06-10 Automake 1.4-p4
2001-07-15 Automake 1.4-p5
Gary continues his patch-release series. These also add support for some new
Autoconf 2.50 idioms. Essentially, Autoconf now advocates configure.ac over
configure.in, and it introduces a new syntax for AC_OUTPUTing files.
2001-08-23 Automake 1.5
A major and long-awaited release, that comes more than two years after 1.4.
It brings many changes, among which:
• The new dependency tracking scheme that uses depcomp. Aside from the
improvement on the dependency tracking itself (see Section 28.2 [Depen-
dency Tracking Evolution], page 143), this also streamlines the use of au-
tomake generated Makefile.ins as the Makefile.ins used during devel-
opment are now the same as those used in distributions. Before that the
Makefile.ins generated for maintainers required GNU make and GCC,
they were different from the portable Makefile generated for distribution;
this was causing some confusion.
• Support for per-target compilation flags.
• Support for reference to files in subdirectories in most Makefile.am vari-
ables.
• Introduction of the dist_, nodist_, and nobase_ prefixes.
• Perl 4 support is finally dropped.
1.5 did break several packages that worked with 1.4. Enough so that Linux dis-
tributions could not easily install the new Automake version without breaking
many of the packages for which they had to run automake.
Some of these breakages were effectively bugs that would eventually be fixed in
the next release. However, a lot of damage was caused by some changes made
deliberately to render Automake stricter on some setup we did consider bogus.
For instance, ‘make distcheck’ was improved to check that ‘make uninstall’
did remove all the files ‘make install’ installed, that ‘make distclean’ did
not omit some file, and that a VPATH build would work even if the source
directory was read-only. Similarly, Automake now rejects multiple definitions
of the same variable (because that would mix very badly with conditionals),
and ‘+=’ assignments with no previous definition. Because these changes all
occurred suddenly after 1.4 had been established for more than two years, it
hurt users.
To make matter worse, meanwhile Autoconf (now at version 2.52) was facing
similar troubles, for similar reasons.
2002-03-05 Automake 1.6
This release introduced versioned installation (see Chapter 25 [API versioning],
page 113). This was mainly pushed by Havoc Pennington, taking the GNOME
source tree as motive: due to incompatibilities between the autotools it’s im-
possible for the GNOME packages to switch to Autoconf 2.53 and Automake
Chapter 28: History of Automake 141
1.5 all at once, so they are currently stuck with Autoconf 2.13 and Automake
1.4.
The idea was to call this version automake-1.6, call all its bug-fix versions iden-
tically, and switch to automake-1.7 for the next release that adds new features
or changes some rules. This scheme implies maintaining a bug-fix branch in ad-
dition to the development trunk, which means more work from the maintainer,
but providing regular bug-fix releases proved to be really worthwhile.
Like 1.5, 1.6 also introduced a bunch of incompatibilities, intentional or not.
Perhaps the more annoying was the dependence on the newly released Autoconf
2.53. Autoconf seemed to have stabilized enough since its explosive 2.50 release
and included changes required to fix some bugs in Automake. In order to
upgrade to Automake 1.6, people now had to upgrade Autoconf too; for some
packages it was no picnic.
While versioned installation helped people to upgrade, it also unfortunately
allowed people not to upgrade. At the time of writing, some Linux distributions
are shipping packages for Automake 1.4, 1.5, 1.6, 1.7, 1.8, and 1.9. Most of these
still install 1.4 by default. Some distribution also call 1.4 the “stable” version,
and present “1.9” as the development version; this does not really makes sense
since 1.9 is way more solid than 1.4. All this does not help the newcomer.
2002-04-11 Automake 1.6.1
1.6, and the upcoming 1.4-p6 release were the last release by Tom. This one and
those following will be handled by Alexandre Duret-Lutz. Tom is still around,
and will be there until about 1.7, but his interest into Automake is drifting
away towards projects like gcj.
Alexandre has been using Automake since 2000, and started to contribute
mostly on Akim’s incitement (Akim and Alexandre have been working in the
same room from 1999 to 2002). In 2001 and 2002 he had a lot of free time to
enjoy hacking Automake.
2002-06-14 Automake 1.6.2
2002-07-28 Automake 1.6.3
2002-07-28 Automake 1.4-p6
Two releases on the same day. 1.6.3 is a bug-fix release.
Tom Tromey backported the versioned installation mechanism on the 1.4
branch, so that Automake 1.6.x and Automake 1.4-p6 could be installed side
by side. Another request from the GNOME folks.
2002-09-25 Automake 1.7
This release switches to the new configure.ac scanner Akim was experiment-
ing in 1.5.
Chapter 28: History of Automake 142
2002-10-16 Automake 1.7.1
2002-12-06 Automake 1.7.2
2003-02-20 Automake 1.7.3
2003-04-23 Automake 1.7.4
2003-05-18 Automake 1.7.5
2003-07-10 Automake 1.7.6
2003-09-07 Automake 1.7.7
2003-10-07 Automake 1.7.8
Many bug-fix releases. 1.7 lasted because the development version (upcoming
1.8) was suffering some major internal revamping.
2003-10-26 Automake on screen
Episode 49, ‘Repercussions’, in the third season of the ‘Alias’ TV show is first
aired.
Marshall, one of the characters, is working on a computer virus that he has
to modify before it gets into the wrong hands or something like that. The
screenshots you see do not show any program code, they show a Makefile.in
generated by automake...
2003-11-09 Automake 1.7.9
2003-12-10 Automake 1.8
The most striking update is probably that of aclocal.
aclocal now uses m4_include in the produced aclocal.m4 when the included
macros are already distributed with the package (an idiom used in many pack-
ages), which reduces code duplication. Many people liked that, but in fact this
change was really introduced to fix a bug in rebuild rules: Makefile.in must
be rebuilt whenever a dependency of configure changes, but all the m4 files
included in aclocal.m4 where unknown from automake. Now automake can
just trace the m4_includes to discover the dependencies.
aclocal also starts using the --trace Autoconf option in order to discover used
macros more accurately. This will turn out to be very tricky (later releases will
improve this) as people had devised many ways to cope with the limitation of
previous aclocal versions, notably using handwritten m4_includes: aclocal
must make sure not to redefine a rule that is already included by such statement.
Automake also has seen its guts rewritten. Although this rewriting took a lot
of efforts, it is only apparent to the users in that some constructions previously
disallowed by the implementation now work nicely. Conditionals, Locations,
Variable and Rule definitions, Options: these items on which Automake works
have been rewritten as separate Perl modules, and documented.
2004-01-11 Automake 1.8.1
2004-01-12 Automake 1.8.2
2004-03-07 Automake 1.8.3
2004-04-25 Automake 1.8.4
2004-05-16 Automake 1.8.5
2004-07-28 Automake 1.9
This release tries to simplify the compilation rules it outputs to reduce the size
of the Makefile. The complaint initially come from the libgcj developers. Their
Chapter 28: History of Automake 143
Makefile.in generated with Automake 1.4 and custom build rules (1.4 did not
support compiled Java) is 250KB. The one generated by 1.8 was over 9MB!
1.9 gets it down to 1.2MB.
Aside from this it contains mainly minor changes and bug-fixes.
2004-08-11 Automake 1.9.1
2004-09-19 Automake 1.9.2
Automake has ten years. This chapter of the manual was initially written for
this occasion.
2007-10-29 Automake repository moves to savannah.gnu.org and uses
git as primary repository.
28.2 Dependency Tracking in Automake
Over the years Automake has deployed three different dependency tracking methods. Each
method, including the current one, has had flaws of various sorts. Here we lay out the
different dependency tracking methods, their flaws, and their fixes. We conclude with rec-
ommendations for tool writers, and by indicating future directions for dependency tracking
work in Automake.
28.2.1 First Take
Description
Our first attempt at automatic dependency tracking was based on the method recommended
by GNU make. (see Section “Generating Prerequisites Automatically” in The GNU make
Manual)
This version worked by precomputing dependencies ahead of time. For each source file,
it had a special .P file that held the dependencies. There was a rule to generate a .P file by
invoking the compiler appropriately. All such .P files were included by the Makefile, thus
implicitly becoming dependencies of Makefile.
Bugs
This approach had several critical bugs.
• The code to generate the .P file relied on gcc. (A limitation, not technically a bug.)
• The dependency tracking mechanism itself relied on GNU make. (A limitation, not
technically a bug.)
• Because each .P file was a dependency of Makefile, this meant that dependency track-
ing was done eagerly by make. For instance, ‘make clean’ would cause all the depen-
dency files to be updated, and then immediately removed. This eagerness also caused
problems with some configurations; if a certain source file could not be compiled on a
given architecture for some reason, dependency tracking would fail, aborting the entire
build.
• As dependency tracking was done as a pre-pass, compile times were doubled–the com-
piler had to be run twice per source file.
• ‘make dist’ re-ran automake to generate a Makefile that did not have automatic
dependency tracking (and that was thus portable to any version of make). In order to
Chapter 28: History of Automake 144
do this portably, Automake had to scan the dependency files and remove any reference
that was to a source file not in the distribution. This process was error-prone. Also, if
‘make dist’ was run in an environment where some object file had a dependency on a
source file that was only conditionally created, Automake would generate a Makefile
that referred to a file that might not appear in the end user’s build. A special, hacky
mechanism was required to work around this.
Historical Note
The code generated by Automake is often inspired by the Makefile style of a particular
author. In the case of the first implementation of dependency tracking, I believe the impetus
and inspiration was Jim Meyering. (I could be mistaken. If you know otherwise feel free to
correct me.)
28.2.2 Dependencies As Side Effects
Description
The next refinement of Automake’s automatic dependency tracking scheme was to imple-
ment dependencies as side effects of the compilation. This was aimed at solving the most
commonly reported problems with the first approach. In particular we were most concerned
with eliminating the weird rebuilding effect associated with make clean.
In this approach, the .P files were included using the -include command, which let us
create these files lazily. This avoided the ‘make clean’ problem.
We only computed dependencies when a file was actually compiled. This avoided the
performance penalty associated with scanning each file twice. It also let us avoid the other
problems associated with the first, eager, implementation. For instance, dependencies would
never be generated for a source file that was not compilable on a given architecture (because
it in fact would never be compiled).
Bugs
• This approach also relied on the existence of gcc and GNU make. (A limitation, not
technically a bug.)
• Dependency tracking was still done by the developer, so the problems from the first
implementation relating to massaging of dependencies by ‘make dist’ were still in effect.
• This implementation suffered from the “deleted header file” problem. Suppose a lazily-
created .P file includes a dependency on a given header file, like this:
maude.o: maude.c something.h
Now suppose that the developer removes something.h and updates maude.c so that
this include is no longer needed. If he runs make, he will get an error because there is
no way to create something.h.
We fixed this problem in a later release by further massaging the output of gcc to
include a dummy dependency for each header file.
28.2.3 Dependencies for the User
Chapter 28: History of Automake 145
Description
The bugs associated with ‘make dist’, over time, became a real problem. Packages using
Automake were being built on a large number of platforms, and were becoming increasingly
complex. Broken dependencies were distributed in “portable” Makefile.ins, leading to
user complaints. Also, the requirement for gcc and GNU make was a constant source
of bug reports. The next implementation of dependency tracking aimed to remove these
problems.
We realized that the only truly reliable way to automatically track dependencies was
to do it when the package itself was built. This meant discovering a method portable
to any version of make and any compiler. Also, we wanted to preserve what we saw as
the best point of the second implementation: dependency computation as a side effect of
compilation.
In the end we found that most modern make implementations support some form of
include directive. Also, we wrote a wrapper script that let us abstract away differences
between dependency tracking methods for compilers. For instance, some compilers cannot
generate dependencies as a side effect of compilation. In this case we simply have the
script run the compiler twice. Currently our wrapper script (depcomp) knows about twelve
different compilers (including a "compiler" that simply invokes makedepend and then the
real compiler, which is assumed to be a standard Unix-like C compiler with no way to do
dependency tracking).
Bugs
• Running a wrapper script for each compilation slows down the build.
• Many users don’t really care about precise dependencies.
• This implementation, like every other automatic dependency tracking scheme in com-
mon use today (indeed, every one we’ve ever heard of), suffers from the “duplicated
new header” bug.
This bug occurs because dependency tracking tools, such as the compiler, only generate
dependencies on the successful opening of a file, and not on every probe.
Suppose for instance that the compiler searches three directories for a given header, and
that the header is found in the third directory. If the programmer erroneously adds a
header file with the same name to the first directory, then a clean rebuild from scratch
could fail (suppose the new header file is buggy), whereas an incremental rebuild will
succeed.
What has happened here is that people have a misunderstanding of what a dependency
is. Tool writers think a dependency encodes information about which files were read
by the compiler. However, a dependency must actually encode information about what
the compiler tried to do.
This problem is not serious in practice. Programmers typically do not use the same
name for a header file twice in a given project. (At least, not in C or C++. This
problem may be more troublesome in Java.) This problem is easy to fix, by modifying
dependency generators to record every probe, instead of every successful open.
• Since automake generates dependencies as a side effect of compilation, there is a boot-
strapping problem when header files are generated by running a program. The problem
Chapter 28: History of Automake 146
is that, the first time the build is done, there is no way by default to know that the
headers are required, so make might try to run a compilation for which the headers
have not yet been built.
This was also a problem in the previous dependency tracking implementation.
The current fix is to use BUILT_SOURCES to list built headers (see Section 9.4 [Sources],
page 80). This causes them to be built before any other build rules are run. This is
unsatisfactory as a general solution, however in practice it seems sufficient for most
actual programs.
This code is used since Automake 1.5.
In GCC 3.0, we managed to convince the maintainers to add special command-line
options to help Automake more efficiently do its job. We hoped this would let us avoid the
use of a wrapper script when Automake’s automatic dependency tracking was used with
gcc.
Unfortunately, this code doesn’t quite do what we want. In particular, it removes the
dependency file if the compilation fails; we’d prefer that it instead only touch the file in any
way if the compilation succeeds.
Nevertheless, since Automake 1.7, when a recent gcc is detected at configure time, we
inline the dependency-generation code and do not use the depcomp wrapper script. This
makes compilations faster for those using this compiler (probably our primary user base).
The counterpart is that because we have to encode two compilation rules in Makefile (with
or without depcomp), the produced Makefiles are larger.
28.2.4 Techniques for Computing Dependencies
There are actually several ways for a build tool like Automake to cause tools to generate
dependencies.
makedepend
This was a commonly-used method in the past. The idea is to run a special
program over the source and have it generate dependency information. Tra-
ditional implementations of makedepend are not completely precise; ordinarily
they were conservative and discovered too many dependencies.
The tool An obvious way to generate dependencies is to simply write the tool so that it
can generate the information needed by the build tool. This is also the most
portable method. Many compilers have an option to generate dependencies.
Unfortunately, not all tools provide such an option.
The file system
It is possible to write a special file system that tracks opens, reads, writes, etc,
and then feed this information back to the build tool. clearmake does this.
This is a very powerful technique, as it doesn’t require cooperation from the
tool. Unfortunately it is also very difficult to implement and also not practical
in the general case.
LD_PRELOAD
Rather than use the file system, one could write a special library to intercept
open and other syscalls. This technique is also quite powerful, but unfortunately
it is not portable enough for use in automake.
Chapter 28: History of Automake 147
28.2.5 Recommendations for Tool Writers
We think that every compilation tool ought to be able to generate dependencies as a side
effect of compilation. Furthermore, at least while make-based tools are nearly universally
in use (at least in the free software community), the tool itself should generate dummy
dependencies for header files, to avoid the deleted header file bug. Finally, the tool should
generate a dependency for each probe, instead of each successful file open, in order to avoid
the duplicated new header bug.
28.2.6 Future Directions for Automake’s Dependency Tracking
Currently, only languages and compilers understood by Automake can have dependency
tracking enabled. We would like to see if it is practical (and worthwhile) to let this support
be extended by the user to languages unknown to Automake.
28.3 Release Statistics
The following table (inspired by ‘perlhist(1)’) quantifies the evolution of Automake using
these metrics:
Date, Rel The date and version of the release.
am The number of lines of the automake script.
acl The number of lines of the aclocal script.
pm The number of lines of the Perl supporting modules.
*.am The number of lines of the Makefile fragments. The number in parentheses is
the number of files.
m4 The number of lines (and files) of Autoconf macros.
doc The number of pages of the documentation (the Postscript version).
t The number of test cases in the test suite. Of those, the number in parentheses
is the number of generated test cases.
Date Rel am acl pm *.am m4 doc t
1994-09-19 CVS 141 299 (24)
1994-11-05 CVS 208 332 (28)
1995-11-23 0.20 533 458 (35) 9
1995-11-26 0.21 613 480 (36) 11
1995-11-28 0.22 1116 539 (38) 12
1995-11-29 0.23 1240 541 (38) 12
1995-12-08 0.24 1462 504 (33) 14
1995-12-10 0.25 1513 511 (37) 15
1996-01-03 0.26 1706 438 (36) 16
1996-01-03 0.27 1706 438 (36) 16
1996-01-13 0.28 1964 934 (33) 16
1996-02-07 0.29 2299 936 (33) 17
1996-02-24 0.30 2544 919 (32) 85 (1) 20 9
1996-03-11 0.31 2877 919 (32) 85 (1) 29 17
Chapter 28: History of Automake 148
1996-04-27 0.32 3058 921 (31) 85 (1) 30 26
1996-05-18 0.33 3110 926 (31) 105 (1) 30 35
1996-05-28 1.0 3134 973 (32) 105 (1) 30 38
1997-06-22 1.2 6089 385 1294 (36) 592 (20) 37 126
1998-04-05 1.3 6415 422 1470 (39) 741 (23) 39 156
1999-01-14 1.4 7240 426 1591 (40) 734 (20) 51 197
2001-05-08 1.4-p1 7251 426 1591 (40) 734 (20) 51 197
2001-05-24 1.4-p2 7268 439 1591 (40) 734 (20) 49 197
2001-06-07 1.4-p3 7312 439 1591 (40) 734 (20) 49 197
2001-06-10 1.4-p4 7321 439 1591 (40) 734 (20) 49 198
2001-07-15 1.4-p5 7228 426 1596 (40) 734 (20) 51 198
2001-08-23 1.5 8016 475 600 2654 (39) 1166 (29) 63 327
2002-03-05 1.6 8465 475 1136 2732 (39) 1603 (27) 66 365
2002-04-11 1.6.1 8544 475 1136 2741 (39) 1603 (27) 66 372
2002-06-14 1.6.2 8575 475 1136 2800 (39) 1609 (27) 67 386
2002-07-28 1.6.3 8600 475 1153 2809 (39) 1609 (27) 67 391
2002-07-28 1.4-p6 7332 455 1596 (40) 735 (20) 49 197
2002-09-25 1.7 9189 471 1790 2965 (39) 1606 (28) 73 430
2002-10-16 1.7.1 9229 475 1790 2977 (39) 1606 (28) 73 437
2002-12-06 1.7.2 9334 475 1790 2988 (39) 1606 (28) 77 445
2003-02-20 1.7.3 9389 475 1790 3023 (39) 1651 (29) 84 448
2003-04-23 1.7.4 9429 475 1790 3031 (39) 1644 (29) 85 458
2003-05-18 1.7.5 9429 475 1790 3033 (39) 1645 (29) 85 459
2003-07-10 1.7.6 9442 475 1790 3033 (39) 1660 (29) 85 461
2003-09-07 1.7.7 9443 475 1790 3041 (39) 1660 (29) 90 467
2003-10-07 1.7.8 9444 475 1790 3041 (39) 1660 (29) 90 468
2003-11-09 1.7.9 9444 475 1790 3048 (39) 1660 (29) 90 468
2003-12-10 1.8 7171 585 7730 3236 (39) 1666 (31) 104 521
2004-01-11 1.8.1 7217 663 7726 3287 (39) 1686 (31) 104 525
2004-01-12 1.8.2 7217 663 7726 3288 (39) 1686 (31) 104 526
2004-03-07 1.8.3 7214 686 7735 3303 (39) 1695 (31) 111 530
2004-04-25 1.8.4 7214 686 7736 3310 (39) 1701 (31) 112 531
2004-05-16 1.8.5 7240 686 7736 3299 (39) 1701 (31) 112 533
2004-07-28 1.9 7508 715 7794 3352 (40) 1812 (32) 115 551
2004-08-11 1.9.1 7512 715 7794 3354 (40) 1812 (32) 115 552
2004-09-19 1.9.2 7512 715 7794 3354 (40) 1812 (32) 132 554
2004-11-01 1.9.3 7507 718 7804 3354 (40) 1812 (32) 134 556
2004-12-18 1.9.4 7508 718 7856 3361 (40) 1811 (32) 140 560
2005-02-13 1.9.5 7523 719 7859 3373 (40) 1453 (32) 142 562
2005-07-10 1.9.6 7539 699 7867 3400 (40) 1453 (32) 144 570
2006-10-15 1.10 7859 1072 8024 3512 (40) 1496 (34) 172 604
2008-01-19 1.10.1 7870 1089 8025 3520 (40) 1499 (34) 173 617
2008-11-23 1.10.2 7882 1089 8027 3540 (40) 1509 (34) 176 628
Appendix A: Copying This Manual 149
Appendix A Copying This Manual
A.1 GNU Free Documentation License
Version 1.3, 3 November 2008
Copyright c 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
http://fsf.org/
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
0. PREAMBLE
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useful document free in the sense of freedom: to assure everyone the effective freedom
to copy and redistribute it, with or without modifying it, either commercially or non-
commercially. Secondarily, this License preserves for the author and publisher a way
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made by others.
This License is a kind of “copyleft”, which means that derivative works of the document
must themselves be free in the same sense. It complements the GNU General Public
License, which is a copyleft license designed for free software.
We have designed this License in order to use it for manuals for free software, because
free software needs free documentation: a free program should come with manuals
providing the same freedoms that the software does. But this License is not limited to
software manuals; it can be used for any textual work, regardless of subject matter or
whether it is published as a printed book. We recommend this License principally for
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Appendix A: Copying This Manual 150
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Appendix A: Copying This Manual 151
2. VERBATIM COPYING
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If you distribute a large enough number of copies you must also follow the conditions
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You may also lend copies, under the same conditions stated above, and you may publicly
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3. COPYING IN QUANTITY
If you publish printed copies (or copies in media that commonly have printed covers) of
the Document, numbering more than 100, and the Document’s license notice requires
Cover Texts, you must enclose the copies in covers that carry, clearly and legibly, all
these Cover Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
the back cover. Both covers must also clearly and legibly identify you as the publisher
of these copies. The front cover must present the full title with all words of the title
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Copying with changes limited to the covers, as long as they preserve the title of the
Document and satisfy these conditions, can be treated as verbatim copying in other
respects.
If the required texts for either cover are too voluminous to fit legibly, you should put
the first ones listed (as many as fit reasonably) on the actual cover, and continue the
rest onto adjacent pages.
If you publish or distribute Opaque copies of the Document numbering more than 100,
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It is requested, but not required, that you contact the authors of the Document well
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with an updated version of the Document.
4. MODIFICATIONS
You may copy and distribute a Modified Version of the Document under the conditions
of sections 2 and 3 above, provided that you release the Modified Version under precisely
this License, with the Modified Version filling the role of the Document, thus licensing
distribution and modification of the Modified Version to whoever possesses a copy of
it. In addition, you must do these things in the Modified Version:
Appendix A: Copying This Manual 152
A. Use in the Title Page (and on the covers, if any) a title distinct from that of the
Document, and from those of previous versions (which should, if there were any,
be listed in the History section of the Document). You may use the same title as
a previous version if the original publisher of that version gives permission.
B. List on the Title Page, as authors, one or more persons or entities responsible for
authorship of the modifications in the Modified Version, together with at least five
of the principal authors of the Document (all of its principal authors, if it has fewer
than five), unless they release you from this requirement.
C. State on the Title page the name of the publisher of the Modified Version, as the
publisher.
D. Preserve all the copyright notices of the Document.
E. Add an appropriate copyright notice for your modifications adjacent to the other
copyright notices.
F. Include, immediately after the copyright notices, a license notice giving the public
permission to use the Modified Version under the terms of this License, in the form
shown in the Addendum below.
G. Preserve in that license notice the full lists of Invariant Sections and required Cover
Texts given in the Document’s license notice.
H. Include an unaltered copy of this License.
I. Preserve the section Entitled “History”, Preserve its Title, and add to it an item
stating at least the title, year, new authors, and publisher of the Modified Version
as given on the Title Page. If there is no section Entitled “History” in the Docu-
ment, create one stating the title, year, authors, and publisher of the Document
as given on its Title Page, then add an item describing the Modified Version as
stated in the previous sentence.
J. Preserve the network location, if any, given in the Document for public access to
a Transparent copy of the Document, and likewise the network locations given in
the Document for previous versions it was based on. These may be placed in the
“History” section. You may omit a network location for a work that was published
at least four years before the Document itself, or if the original publisher of the
version it refers to gives permission.
K. For any section Entitled “Acknowledgements” or “Dedications”, Preserve the Title
of the section, and preserve in the section all the substance and tone of each of the
contributor acknowledgements and/or dedications given therein.
L. Preserve all the Invariant Sections of the Document, unaltered in their text and
in their titles. Section numbers or the equivalent are not considered part of the
section titles.
M. Delete any section Entitled “Endorsements”. Such a section may not be included
in the Modified Version.
N. Do not retitle any existing section to be Entitled “Endorsements” or to conflict in
title with any Invariant Section.
O. Preserve any Warranty Disclaimers.
If the Modified Version includes new front-matter sections or appendices that qualify
as Secondary Sections and contain no material copied from the Document, you may at
Appendix A: Copying This Manual 153
your option designate some or all of these sections as invariant. To do this, add their
titles to the list of Invariant Sections in the Modified Version’s license notice. These
titles must be distinct from any other section titles.
You may add a section Entitled “Endorsements”, provided it contains nothing but
endorsements of your Modified Version by various parties—for example, statements of
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definition of a standard.
You may add a passage of up to five words as a Front-Cover Text, and a passage of up
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includes a cover text for the same cover, previously added by you or by arrangement
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you may replace the old one, on explicit permission from the previous publisher that
added the old one.
The author(s) and publisher(s) of the Document do not by this License give permission
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5. COMBINING DOCUMENTS
You may combine the Document with other documents released under this License,
under the terms defined in section 4 above for modified versions, provided that you
include in the combination all of the Invariant Sections of all of the original documents,
unmodified, and list them all as Invariant Sections of your combined work in its license
notice, and that you preserve all their Warranty Disclaimers.
The combined work need only contain one copy of this License, and multiple identical
Invariant Sections may be replaced with a single copy. If there are multiple Invariant
Sections with the same name but different contents, make the title of each such section
unique by adding at the end of it, in parentheses, the name of the original author or
publisher of that section if known, or else a unique number. Make the same adjustment
to the section titles in the list of Invariant Sections in the license notice of the combined
work.
In the combination, you must combine any sections Entitled “History” in the vari-
ous original documents, forming one section Entitled “History”; likewise combine any
sections Entitled “Acknowledgements”, and any sections Entitled “Dedications”. You
must delete all sections Entitled “Endorsements.”
6. COLLECTIONS OF DOCUMENTS
You may make a collection consisting of the Document and other documents released
under this License, and replace the individual copies of this License in the various
documents with a single copy that is included in the collection, provided that you
follow the rules of this License for verbatim copying of each of the documents in all
other respects.
You may extract a single document from such a collection, and distribute it individu-
ally under this License, provided you insert a copy of this License into the extracted
document, and follow this License in all other respects regarding verbatim copying of
that document.
Appendix A: Copying This Manual 154
7. AGGREGATION WITH INDEPENDENT WORKS
A compilation of the Document or its derivatives with other separate and independent
documents or works, in or on a volume of a storage or distribution medium, is called
an “aggregate” if the copyright resulting from the compilation is not used to limit the
legal rights of the compilation’s users beyond what the individual works permit. When
the Document is included in an aggregate, this License does not apply to the other
works in the aggregate which are not themselves derivative works of the Document.
If the Cover Text requirement of section 3 is applicable to these copies of the Document,
then if the Document is less than one half of the entire aggregate, the Document’s Cover
Texts may be placed on covers that bracket the Document within the aggregate, or the
electronic equivalent of covers if the Document is in electronic form. Otherwise they
must appear on printed covers that bracket the whole aggregate.
8. TRANSLATION
Translation is considered a kind of modification, so you may distribute translations
of the Document under the terms of section 4. Replacing Invariant Sections with
translations requires special permission from their copyright holders, but you may
include translations of some or all Invariant Sections in addition to the original versions
of these Invariant Sections. You may include a translation of this License, and all the
license notices in the Document, and any Warranty Disclaimers, provided that you
also include the original English version of this License and the original versions of
those notices and disclaimers. In case of a disagreement between the translation and
the original version of this License or a notice or disclaimer, the original version will
prevail.
If a section in the Document is Entitled “Acknowledgements”, “Dedications”, or “His-
tory”, the requirement (section 4) to Preserve its Title (section 1) will typically require
changing the actual title.
9. TERMINATION
You may not copy, modify, sublicense, or distribute the Document except as expressly
provided under this License. Any attempt otherwise to copy, modify, sublicense, or
distribute it is void, and will automatically terminate your rights under this License.
However, if you cease all violation of this License, then your license from a particular
copyright holder is reinstated (a) provisionally, unless and until the copyright holder
explicitly and finally terminates your license, and (b) permanently, if the copyright
holder fails to notify you of the violation by some reasonable means prior to 60 days
after the cessation.
Moreover, your license from a particular copyright holder is reinstated permanently if
the copyright holder notifies you of the violation by some reasonable means, this is the
first time you have received notice of violation of this License (for any work) from that
copyright holder, and you cure the violation prior to 30 days after your receipt of the
notice.
Termination of your rights under this section does not terminate the licenses of parties
who have received copies or rights from you under this License. If your rights have
been terminated and not permanently reinstated, receipt of a copy of some or all of the
same material does not give you any rights to use it.
Appendix A: Copying This Manual 155
10. FUTURE REVISIONS OF THIS LICENSE
The Free Software Foundation may publish new, revised versions of the GNU Free
Documentation License from time to time. Such new versions will be similar in spirit
to the present version, but may differ in detail to address new problems or concerns.
See http://www.gnu.org/copyleft/.
Each version of the License is given a distinguishing version number. If the Document
specifies that a particular numbered version of this License “or any later version”
applies to it, you have the option of following the terms and conditions either of that
specified version or of any later version that has been published (not as a draft) by
the Free Software Foundation. If the Document does not specify a version number of
this License, you may choose any version ever published (not as a draft) by the Free
Software Foundation. If the Document specifies that a proxy can decide which future
versions of this License can be used, that proxy’s public statement of acceptance of a
version permanently authorizes you to choose that version for the Document.
11. RELICENSING
“Massive Multiauthor Collaboration Site” (or “MMC Site”) means any World Wide
Web server that publishes copyrightable works and also provides prominent facilities
for anybody to edit those works. A public wiki that anybody can edit is an example of
such a server. A “Massive Multiauthor Collaboration” (or “MMC”) contained in the
site means any set of copyrightable works thus published on the MMC site.
“CC-BY-SA” means the Creative Commons Attribution-Share Alike 3.0 license pub-
lished by Creative Commons Corporation, a not-for-profit corporation with a principal
place of business in San Francisco, California, as well as future copyleft versions of that
license published by that same organization.
“Incorporate” means to publish or republish a Document, in whole or in part, as part
of another Document.
An MMC is “eligible for relicensing” if it is licensed under this License, and if all works
that were first published under this License somewhere other than this MMC, and
subsequently incorporated in whole or in part into the MMC, (1) had no cover texts
or invariant sections, and (2) were thus incorporated prior to November 1, 2008.
The operator of an MMC Site may republish an MMC contained in the site under
CC-BY-SA on the same site at any time before August 1, 2009, provided the MMC is
eligible for relicensing.
Appendix A: Copying This Manual 156
ADDENDUM: How to use this License for your documents
To use this License in a document you have written, include a copy of the License in the
document and put the following copyright and license notices just after the title page:
Copyright (C) year your name.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3
or any later version published by the Free Software Foundation;
with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
Texts. A copy of the license is included in the section entitled ‘‘GNU
Free Documentation License’’.
If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, replace the
“with. . . Texts.” line with this:
with the Invariant Sections being list their titles, with
the Front-Cover Texts being list, and with the Back-Cover Texts
being list.
If you have Invariant Sections without Cover Texts, or some other combination of the
three, merge those two alternatives to suit the situation.
If your document contains nontrivial examples of program code, we recommend releasing
these examples in parallel under your choice of free software license, such as the GNU
General Public License, to permit their use in free software.
Appendix B: Indices 157
Appendix B Indices
B.1 Macro Index
AC_REQUIRE_AUX_FILE. . . . . . . . . . . . . . . . . . . . . . . . . . 32
_AM_DEPENDENCIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 AC_SUBST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
AM_C_PROTOTYPES . . . . . . . . . . . . . . . . . . . . . . . 32, 44, 77
AM_COND_IF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32, 106
A AM_CONDITIONAL. . . . . . . . . . . . . . . . . . . . . . . . . . . 32, 105
AM_CONFIG_HEADER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
AC_CANONICAL_BUILD . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 AM_DEP_TRACK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
AC_CANONICAL_HOST . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 AM_ENABLE_MULTILIB . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
AC_CANONICAL_TARGET. . . . . . . . . . . . . . . . . . . . . . . . . . 30 AM_GNU_GETTEXT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
AC_CONFIG_AUX_DIR . . . . . . . . . . . . . . . . . . . . . . . . 30, 49 AM_GNU_GETTEXT_INTL_SUBDIR. . . . . . . . . . . . . . . . . . 32
AC_CONFIG_FILES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 AM_HEADER_TIOCGWINSZ_NEEDS_SYS_IOCTL . . . . . . 44
AC_CONFIG_HEADERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 AM_INIT_AUTOMAKE . . . . . . . . . . . . . . . . . . . . . . . . . 28, 42
AC_CONFIG_LIBOBJ_DIR . . . . . . . . . . . . . . . . . . . . . 30, 67 AM_MAINTAINER_MODE . . . . . . . . . . . . . . . . . . 33, 98, 117
AC_CONFIG_LINKS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 AM_MAKE_INCLUDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
AC_CONFIG_SUBDIRS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 AM_OUTPUT_DEPENDENCY_COMMANDS . . . . . . . . . . . . . . 45
AC_DEFUN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 AM_PATH_LISPDIR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
AC_F77_LIBRARY_LDFLAGS . . . . . . . . . . . . . . . . . . . . . . 31 AM_PATH_PYTHON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
AC_FC_SRCEXT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 AM_PROG_AS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
AC_INIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 AM_PROG_CC_C_O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
AC_LIBOBJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31, 60, 66 AM_PROG_GCJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
AC_LIBSOURCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31, 66 AM_PROG_INSTALL_STRIP . . . . . . . . . . . . . . . . . . . . . . . 45
AC_LIBSOURCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 AM_PROG_LEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
AC_OUTPUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 AM_PROG_MKDIR_P . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
AC_PREREQ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 AM_PROG_UPC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
AC_PROG_CC_C_O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 AM_SANITY_CHECK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
AC_PROG_CXX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 AM_SET_DEPDIR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
AC_PROG_F77 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 AM_SYS_POSIX_TERMIOS . . . . . . . . . . . . . . . . . . . . . . . . 44
AC_PROG_FC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 AM_WITH_DMALLOC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
AC_PROG_LEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32, 43 AM_WITH_REGEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
AC_PROG_LIBTOOL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
AC_PROG_OBJC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
AC_PROG_RANLIB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 M
AC_PROG_YACC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 m4_include . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33, 93
B.2 Variable Index
A
_DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 ACLOCAL_AMFLAGS. . . . . . . . . . . . . . . . . . . . . . . . . . . 38, 98
_HEADERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 ALLOCA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60, 66
_LIBRARIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 AM_CCASFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
_LISP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 AM_CFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
_LTLIBRARIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 AM_COLOR_TESTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
_MANS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 AM_CPPFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68, 72
_PROGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19, 51 AM_CXXFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
_PYTHON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 AM_ETAGSFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
_SCRIPTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 AM_FCFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
_SOURCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51, 65 AM_FFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
_TEXINFOS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88, 89 AM_GCJFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
AM_INSTALLCHECK_STD_OPTIONS_EXEMPT . . . . . . . 101
AM_JAVACFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Appendix B: Indices 158
AM_LDFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52, 68 distdir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94, 110
AM_LFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 distuninstallcheck_listfiles . . . . . . . . . . . . . . . 95
AM_LIBTOOLFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 DVIPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
AM_MAKEFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
AM_MAKEINFOFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
AM_MAKEINFOHTMLFLAGS . . . . . . . . . . . . . . . . . . . . . . . . 89 E
AM_OBJCFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
AM_RFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 EMACS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
AM_RUNTESTFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 ETAGS_ARGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
AM_UPCFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 ETAGSFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
AM_YFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 EXPECT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
ANSI2KNR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 EXTRA_DIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
AUTOCONF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 EXTRA_maude_SOURCES. . . . . . . . . . . . . . . . . . . . . . . . . . 62
AUTOM4TE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 EXTRA_PROGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
AUTOMAKE_OPTIONS . . . . . . . . . . . . . . . . . . 42, 76, 77, 99
F
B F77 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
bin_PROGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 F77COMPILE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
bin_SCRIPTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 F77LINK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
build_triplet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 FC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
BUILT_SOURCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 FCCOMPILE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
FCFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
FCLINK. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
C FFLAGS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
CC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 FLIBS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
CCAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43, 72 FLINK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
CCASFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43, 72
CFLAGS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
check_. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 G
check_LTLIBRARIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
check_PROGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51, 66 GCJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
check_SCRIPTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 GCJFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43, 76
CLASSPATH_ENV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 GCJLINK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
CLEANFILES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 GTAGS_ARGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
COMPILE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 GZIP_ENV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
CONFIG_STATUS_DEPENDENCIES. . . . . . . . . . . . . . . . . . 98
CONFIGURE_DEPENDENCIES . . . . . . . . . . . . . . . . . . . . . . 98
CPPFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68, 72 H
CXX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 HEADERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
CXXCOMPILE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 host_triplet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
CXXFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
CXXLINK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71, 75
I
D include_HEADERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
data_DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 INCLUDES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20, 80 info_TEXINFOS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
DEFS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
DEJATOOL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
DESTDIR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10, 92 J
dist_ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49, 94
dist_lisp_LISP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 JAVA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
dist_noinst_LISP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 JAVAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
DIST_SUBDIRS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47, 94 JAVACFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
DISTCHECK_CONFIGURE_FLAGS . . . . . . . . . . . . . . . . . . . 95 JAVAROOT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
distcleancheck_listfiles . . . . . . . . . . . . . . . 95, 121
DISTCLEANFILES . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93, 95
Appendix B: Indices 159
L N
LDADD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 nobase_ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
LDFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 nodist_ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49, 94
LFLAGS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 noinst_ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
lib_LIBRARIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 noinst_HEADERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
lib_LTLIBRARIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 noinst_LIBRARIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
libexec_PROGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 noinst_LISP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
libexec_SCRIPTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 noinst_LTLIBRARIES . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
LIBOBJS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31, 60, 66 noinst_PROGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
LIBRARIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 noinst_SCRIPTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
LIBS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 notrans_ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
LIBTOOLFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
LINK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69, 75
lisp_LISP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
lispdir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
O
LISP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 OBJC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
localstate_DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 OBJCCOMPILE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
LTALLOCA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60, 66 OBJCFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
LTLIBOBJS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60, 66 OBJCLINK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71, 75
oldinclude_HEADERS . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
M
MAINTAINERCLEANFILES . . . . . . . . . . . . . . . . . . . . . . . . 93
P
MAKE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 PACKAGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
MAKEINFO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 pkgdata_DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
MAKEINFOFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 pkgdata_SCRIPTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
MAKEINFOHTML . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 pkgdatadir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
man_MANS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 pkginclude_HEADERS . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
MANS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 pkgincludedir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
maude_AR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 pkglib_LIBRARIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
maude_CCASFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 pkglib_LTLIBRARIES . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
maude_CFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 pkglib_PROGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
maude_CPPFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 pkglibdir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
maude_CXXFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 pkglibexecdir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
maude_DEPENDENCIES . . . . . . . . . . . . . . . . . . . . . . . 52, 64 pkgpyexecdir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
maude_FFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 pkgpythondir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
maude_GCJFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 PROGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
maude_LDADD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52, 63 pyexecdir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
maude_LDFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52, 63 PYTHON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20, 87
maude_LFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 PYTHON_EXEC_PREFIX . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
maude_LIBADD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55, 63 PYTHON_PLATFORM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
maude_LIBTOOLFLAGS . . . . . . . . . . . . . . . . . . . . . . . 60, 63 PYTHON_PREFIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
maude_LINK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 PYTHON_VERSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
maude_OBJCFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 pythondir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
maude_RFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
maude_SHORTNAME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
maude_SOURCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 R
maude_UPCFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
maude_YFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 RFLAGS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
mkdir_p . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 RUNTEST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
MKDIR_P . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 RUNTESTDEFAULTFLAGS. . . . . . . . . . . . . . . . . . . . . . . . . . 98
MOSTLYCLEANFILES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 RUNTESTFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Appendix B: Indices 160
S U
sbin_PROGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 U .............................................. 44
sbin_SCRIPTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 UPC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43, 72
UPCCOMPILE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
SCRIPTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20, 79
UPCFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
sharedstate_DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 UPCLINK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72, 75
SOURCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51, 65
SUBDIRS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45, 94
SUFFIXES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 V
sysconf_DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 VERSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
W
WARNINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27, 35
T WITH_DMALLOC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
WITH_REGEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
TAGS_DEPENDENCIES . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
target_triplet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
TESTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 X
TESTS_ENVIRONMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 XFAIL_TESTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
TEXI2DVI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
TEXI2PDF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
TEXINFO_TEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 Y
TEXINFOS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20, 89 YACC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
top_distdir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94, 110 YFLAGS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
B.3 General Index
# --foreign . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
## (special Automake comment). . . . . . . . . . . . . . . . 19 --gnits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
#serial syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 --gnits, complete description . . . . . . . . . . . . . . . . . 107
--gnu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
--gnu, complete description . . . . . . . . . . . . . . . . . . . 107
$ --gnu, required files . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
--help . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26, 34
‘$(LIBOBJS)’ and empty libraries . . . . . . . . . . . . . . . 67 --help check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
--help=recursive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
--host=HOST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
+ --include-deps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
+= . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 --install . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
--libdir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
--no-force . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
– --output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
--acdir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 --output-dir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
--add-missing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 --prefix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
--build=BUILD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 --print-ac-dir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
--copy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 --program-prefix=PREFIX . . . . . . . . . . . . . . . . . . . . . 10
--cygnus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 --program-suffix=SUFFIX . . . . . . . . . . . . . . . . . . . . . 10
--diff. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 --program-transform-name=PROGRAM . . . . . . . . . . . 10
--disable-dependency-tracking . . . . . . . . . . . . . . 12 --target=TARGET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
--dry-run . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 --verbose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27, 34
--enable-debug, example . . . . . . . . . . . . . . . . . . . . . 105 --version . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27, 34
--enable-dependency-tracking . . . . . . . . . . . . . . . 12 --version check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
--enable-maintainer-mode . . . . . . . . . . . . . . . . . . . . 33 --warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27, 35
--force . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 --with-dmalloc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
--force-missing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 --with-regex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Appendix B: Indices 161
-a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 ALLOCA, and Libtool . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
-c . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 ALLOCA, example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
-f . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 ALLOCA, special handling . . . . . . . . . . . . . . . . . . . . . . . 66
-hook targets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 AM_CCASFLAGS and CCASFLAGS . . . . . . . . . . . . . . . . . 122
-i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 AM_CFLAGS and CFLAGS . . . . . . . . . . . . . . . . . . . . . . . . 122
-I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 AM_CONDITIONAL and SUBDIRS . . . . . . . . . . . . . . . . . . 47
-l and LDADD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 AM_CPPFLAGS and CPPFLAGS . . . . . . . . . . . . . . . . . . . 122
-local targets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 AM_CXXFLAGS and CXXFLAGS . . . . . . . . . . . . . . . . . . . 122
-module, libtool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 AM_FCFLAGS and FCFLAGS . . . . . . . . . . . . . . . . . . . . . . 122
-o . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 AM_FFLAGS and FFLAGS . . . . . . . . . . . . . . . . . . . . . . . . 122
-v . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 AM_GCJFLAGS and GCJFLAGS . . . . . . . . . . . . . . . . . . . 122
-W . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27, 35 AM_INIT_AUTOMAKE, example use . . . . . . . . . . . . . . . . 23
-Wall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 AM_LDFLAGS and LDFLAGS . . . . . . . . . . . . . . . . . . . . . . 122
-Werror . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 AM_LFLAGS and LFLAGS . . . . . . . . . . . . . . . . . . . . . . . . 122
AM_LIBTOOLFLAGS and LIBTOOLFLAGS . . . . . . . . . . 122
. AM_MAINTAINER_MODE, purpose. . . . . . . . . . . . . . . . . 117
AM_OBJCFLAGS and OBJCFLAGS . . . . . . . . . . . . . . . . . 122
.la suffix, defined . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 AM_RFLAGS and RFLAGS . . . . . . . . . . . . . . . . . . . . . . . . 122
AM_UPCFLAGS and UPCFLAGS . . . . . . . . . . . . . . . . . . . 122
AM_YFLAGS and YFLAGS . . . . . . . . . . . . . . . . . . . . . . . . 122
amhello-1.0.tar.gz, creation . . . . . . . . . . . . . . . . . 13
_DATA primary, defined . . . . . . . . . . . . . . . . . . . . . . . . . 80 amhello-1.0.tar.gz, location . . . . . . . . . . . . . . . . . . . 2
_DEPENDENCIES, defined . . . . . . . . . . . . . . . . . . . . . . . . 52 amhello-1.0.tar.gz, use cases . . . . . . . . . . . . . . . . . . 2
_HEADERS primary, defined . . . . . . . . . . . . . . . . . . . . . 80 ansi2knr . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76, 100
_JAVA primary, defined . . . . . . . . . . . . . . . . . . . . . . . . . 85 ansi2knr and LIBOBJS . . . . . . . . . . . . . . . . . . . . . . . . . 77
_LDFLAGS, defined . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 ansi2knr and LTLIBOBJS . . . . . . . . . . . . . . . . . . . . . . . 77
_LDFLAGS, libtool. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Append operator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
_LIBADD, libtool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
autogen.sh and autoreconf . . . . . . . . . . . . . . . . . . . 61
_LIBRARIES primary, defined . . . . . . . . . . . . . . . . . . . 55
autom4te . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
_LIBTOOLFLAGS, libtool . . . . . . . . . . . . . . . . . . . . . . . . . 60
Automake constraints . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
_LISP primary, defined . . . . . . . . . . . . . . . . . . . . . . . . . 84
automake options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
_LTLIBRARIES primary, defined . . . . . . . . . . . . . . . . . 56
Automake requirements . . . . . . . . . . . . . . . . . . . . . 1, 28
_MANS primary, defined . . . . . . . . . . . . . . . . . . . . . . . . . 90
_PROGRAMS primary variable . . . . . . . . . . . . . . . . . . . . 19 automake, invoking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
_PYTHON primary, defined . . . . . . . . . . . . . . . . . . . . . . . 86 Automake, recursive operation . . . . . . . . . . . . . . . . . 18
_SCRIPTS primary, defined . . . . . . . . . . . . . . . . . . . . . 79 Automatic dependency tracking . . . . . . . . . . . . . . . . 77
_SOURCES and header files . . . . . . . . . . . . . . . . . . . . . . 51 Automatic linker selection . . . . . . . . . . . . . . . . . . . . . . 75
_SOURCES primary, defined . . . . . . . . . . . . . . . . . . . . . 51 autoreconf and libtoolize . . . . . . . . . . . . . . . . . . . 61
_SOURCES, default . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 autoreconf, example . . . . . . . . . . . . . . . . . . . . . . . . . . 14
_SOURCES, empty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 autoscan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
_TEXINFOS primary, defined . . . . . . . . . . . . . . . . . . . . 88 Autotools, introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
Autotools, purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
autoupdate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
A Auxiliary programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Avoiding man page renaming . . . . . . . . . . . . . . . . . . 90
AC_CONFIG_FILES, conditional . . . . . . . . . . . . . . . . . 106
AC_SUBST and SUBDIRS . . . . . . . . . . . . . . . . . . . . . . . . . 47 Avoiding path stripping . . . . . . . . . . . . . . . . . . . . . . . . 49
acinclude.m4, defined . . . . . . . . . . . . . . . . . . . . . . . . . 23
aclocal and serial numbers . . . . . . . . . . . . . . . . . . . . 39
aclocal program, introduction . . . . . . . . . . . . . . . . . 23 B
aclocal search path . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Binary package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
aclocal’s scheduled death . . . . . . . . . . . . . . . . . . . . . 41
bootstrap.sh and autoreconf . . . . . . . . . . . . . . . . . 61
aclocal, extending . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Bugs, reporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
aclocal, Invoking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
aclocal, Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 build tree and source tree . . . . . . . . . . . . . . . . . . . . . . . 6
aclocal.m4, preexisting . . . . . . . . . . . . . . . . . . . . . . . . 23 BUILT_SOURCES, defined . . . . . . . . . . . . . . . . . . . . . . . . 81
Adding new SUFFIXES. . . . . . . . . . . . . . . . . . . . . . . . . 104
all . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4, 109
all-local . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Appendix B: Indices 162
C directory variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
C++ support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 dirlist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
canonicalizing Automake variables. . . . . . . . . . . . . . 21 Disabling dependency tracking . . . . . . . . . . . . . . . . . 78
CCASFLAGS and AM_CCASFLAGS . . . . . . . . . . . . . . . . . 122 dist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4, 93
CFLAGS and AM_CFLAGS . . . . . . . . . . . . . . . . . . . . . . . . 122 dist-bzip2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96, 100
cfortran . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 dist-gzip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4, 97, 109 dist-hook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94, 109
check-local . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 dist-lzma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96, 100
check-news . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 dist-shar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96, 100
‘check_’ primary prefix, definition . . . . . . . . . . . . . . 20 dist-tarZ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96, 100
check_PROGRAMS example . . . . . . . . . . . . . . . . . . . . . . 66 dist-zip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96, 100
clean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4, 109 dist_ and nobase_ . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
clean-local . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93, 109 dist_ and notrans_ . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
color-tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 DIST_SUBDIRS, explained . . . . . . . . . . . . . . . . . . . . . . . 46
Comment, special to Automake . . . . . . . . . . . . . . . . 19 distcheck . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15, 95
Compile Flag Variables . . . . . . . . . . . . . . . . . . . . . . . 122 distcheck better than dist . . . . . . . . . . . . . . . . . . . . 11
Complete example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 distcheck example . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Conditional example, --enable-debug . . . . . . . . 105 distcheck-hook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
conditional libtool libraries . . . . . . . . . . . . . . . . . . . . . 57 distclean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4, 109, 120
Conditional programs . . . . . . . . . . . . . . . . . . . . . . . . . . 54 distclean, diagnostic . . . . . . . . . . . . . . . . . . . . . . . . . 120
Conditional subdirectories. . . . . . . . . . . . . . . . . . . . . . 46 distclean-local . . . . . . . . . . . . . . . . . . . . . . . . . 93, 109
Conditional SUBDIRS . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 distcleancheck. . . . . . . . . . . . . . . . . . . . . . . . . . . 95, 120
Conditionals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 distdir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
config.guess . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Distributions, preparation . . . . . . . . . . . . . . . . . . . . . . 11
config.site example . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 dmalloc, support for . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
configuration variables, overriding . . . . . . . . . . . . . . . 5 dvi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88, 109
Configuration, basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 dvi-local . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
configure.ac, scanning . . . . . . . . . . . . . . . . . . . . . . . . 28 DVI output using Texinfo . . . . . . . . . . . . . . . . . . . . . . 88
conflicting definitions . . . . . . . . . . . . . . . . . . . . . . . . . 109
Constraints of Automake . . . . . . . . . . . . . . . . . . . . . . . . 1
convenience libraries, libtool . . . . . . . . . . . . . . . . . . . 58 E
copying semantics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
E-mail, bug reports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
cpio example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
EDITION Texinfo flag . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
CPPFLAGS and AM_CPPFLAGS . . . . . . . . . . . . . . . . . . . 122
else . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
cross-compilation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
empty _SOURCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
cross-compilation example . . . . . . . . . . . . . . . . . . . . . . . 9
Empty libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
cvs-dist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Empty libraries and ‘$(LIBOBJS)’ . . . . . . . . . . . . . . 67
cvs-dist, non-standard example . . . . . . . . . . . . . . . 18
endif. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
CVS and generated files . . . . . . . . . . . . . . . . . . . . . . . 115
Example conditional --enable-debug . . . . . . . . . 105
CVS and third-party files . . . . . . . . . . . . . . . . . . . . . 117
Example conditional AC_CONFIG_FILES . . . . . . . . 106
CVS and timestamps . . . . . . . . . . . . . . . . . . . . . . . . . 115
Example Hello World . . . . . . . . . . . . . . . . . . . . . . . . . . 13
CXXFLAGS and AM_CXXFLAGS . . . . . . . . . . . . . . . . . . . 122
Example of recursive operation . . . . . . . . . . . . . . . . . 18
cygnus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Example of shared libraries . . . . . . . . . . . . . . . . . . . . 56
cygnus strictness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
Example, EXTRA_PROGRAMS . . . . . . . . . . . . . . . . . . . . . 20
Example, false and true . . . . . . . . . . . . . . . . . . . . . . 24
D Example, mixed language . . . . . . . . . . . . . . . . . . . . . . 74
Executable extension . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
DATA primary, defined . . . . . . . . . . . . . . . . . . . . . . . . . . 80 Exit status 77, special interpretation . . . . . . . . . . . 97
de-ANSI-fication, defined . . . . . . . . . . . . . . . . . . . . . . . 76 Expected test failure . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
debug build, example . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Extending aclocal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
default _SOURCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 Extending list of installation directories . . . . . . . . 20
default source, Libtool modules example . . . . . . . . 66 Extension, executable . . . . . . . . . . . . . . . . . . . . . . . . . . 78
definitions, conflicts . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 Extra files distributed with Automake . . . . . . . . . . 25
dejagnu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98, 100 EXTRA_, prepending . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
depcomp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 EXTRA_prog_SOURCES, defined . . . . . . . . . . . . . . . . . . 53
dependencies and distributed files . . . . . . . . . . . . . 120 EXTRA_PROGRAMS, defined . . . . . . . . . . . . . . . . . . . 20, 54
Dependency tracking . . . . . . . . . . . . . . . . . . . . . . . 11, 77
Dependency tracking, disabling. . . . . . . . . . . . . . . . . 78
Appendix B: Indices 163
F I
false Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 id . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
FCFLAGS and AM_FCFLAGS . . . . . . . . . . . . . . . . . . . . . . 122 if . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Features of the GNU Build System . . . . . . . . . . . . . . 2 include . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93, 104
FFLAGS and AM_FFLAGS . . . . . . . . . . . . . . . . . . . . . . . . 122 include, distribution . . . . . . . . . . . . . . . . . . . . . . . . . . 93
file names, limitations on . . . . . . . . . . . . . . . . . . . . . 119 Including Makefile fragment . . . . . . . . . . . . . . . . . . 104
filename-length-max=99 . . . . . . . . . . . . . . . . . . . . . 100 info . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101, 109
Files distributed with Automake . . . . . . . . . . . . . . . 25 info-local . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
First line of Makefile.am . . . . . . . . . . . . . . . . . . . . . . . 19 install . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4, 91, 109
Flag variables, ordering . . . . . . . . . . . . . . . . . . . . . . . 121 Install hook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
Flag Variables, Ordering . . . . . . . . . . . . . . . . . . . . . . 122 Install, two parts of . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
FLIBS, defined . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 install-data . . . . . . . . . . . . . . . . . . . . . . . . . . 8, 91, 109
foreign . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16, 99 install-data-hook . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
foreign strictness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 install-data-local . . . . . . . . . . . . . . . . . . . . . . 92, 109
Fortran 77 support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 install-dvi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88, 109
Fortran 77, mixing with C and C++ . . . . . . . . . . . . 73 install-dvi-local . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Fortran 77, Preprocessing . . . . . . . . . . . . . . . . . . . . . . 73 install-exec . . . . . . . . . . . . . . . . . . . . . . . . . . 8, 91, 109
Fortran 9x support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 install-exec-hook . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
install-exec-local . . . . . . . . . . . . . . . . . . . . . . 92, 109
install-html . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88, 109
G install-html-local . . . . . . . . . . . . . . . . . . . . . . . . . . 109
install-info . . . . . . . . . . . . . . . . . . . . . . . . 89, 101, 109
GCJFLAGS and AM_GCJFLAGS . . . . . . . . . . . . . . . . . . . 122 install-info target . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
generated files and CVS . . . . . . . . . . . . . . . . . . . . . . . 115
install-info-local . . . . . . . . . . . . . . . . . . . . . . . . . . 109
generated files, distributed . . . . . . . . . . . . . . . . . . . . 115
install-man . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90, 101
Gettext support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
install-man target . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
git-dist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
install-pdf . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88, 109
gnits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
install-pdf-local . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
gnits strictness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
install-ps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88, 109
gnu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
install-ps-local . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
gnu strictness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
install-strip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4, 92
GNU Build System, basics . . . . . . . . . . . . . . . . . . . . . . 3
Installation directories, extending list . . . . . . . . . . . 20
GNU Build System, features . . . . . . . . . . . . . . . . . . . . 2
Installation support . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
GNU Build System, introduction . . . . . . . . . . . . . . . . 1
Installation, basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
GNU Build System, use cases . . . . . . . . . . . . . . . . . . . 2
installcheck . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4, 109
GNU Coding Standards . . . . . . . . . . . . . . . . . . . . . . . . . 2
installcheck-local . . . . . . . . . . . . . . . . . . . . . . . . . . 109
GNU Gettext support . . . . . . . . . . . . . . . . . . . . . . . . . . 85
installdirs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92, 109
GNU make extensions. . . . . . . . . . . . . . . . . . . . . . . . . . 18
installdirs-local . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
GNU Makefile standards . . . . . . . . . . . . . . . . . . . . . . . . 1
GNUmakefile including Makefile . . . . . . . . . . . . . . 112 Installing headers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Installing scripts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
installing versioned binaries . . . . . . . . . . . . . . . . . . . 110
Interfacing with third-party packages . . . . . . . . . . 110
H Invoking aclocal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Header files in _SOURCES . . . . . . . . . . . . . . . . . . . . . . . 51 Invoking automake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
HEADERS primary, defined . . . . . . . . . . . . . . . . . . . . . . . 80
HEADERS, installation directories . . . . . . . . . . . . . . . . 80
Hello World example . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
hook targets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
J
HP-UX 10, lex problems . . . . . . . . . . . . . . . . . . . . . . . 43 Java support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
html . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88, 109 JAVA primary, defined . . . . . . . . . . . . . . . . . . . . . . . . . . 85
html-local . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 JAVA restrictions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
HTML output using Texinfo . . . . . . . . . . . . . . . . . . . 88
Appendix B: Indices 164
L missing, purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
LDADD and -l . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Mixed language example . . . . . . . . . . . . . . . . . . . . . . . 74
LDFLAGS and AM_LDFLAGS . . . . . . . . . . . . . . . . . . . . . . 122 Mixing Fortran 77 with C and C++ . . . . . . . . . . . . . 73
lex problems with HP-UX 10 . . . . . . . . . . . . . . . . . . 43 Mixing Fortran 77 with C and/or C++ . . . . . . . . . . 73
lex, multiple lexers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 mkdir -p, macro check . . . . . . . . . . . . . . . . . . . . . . . . . 44
LFLAGS and AM_LFLAGS . . . . . . . . . . . . . . . . . . . . . . . . 122 modules, libtool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
libltdl, introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 56 mostlyclean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
LIBOBJS and ansi2knr . . . . . . . . . . . . . . . . . . . . . . . . . 77 mostlyclean-local . . . . . . . . . . . . . . . . . . . . . . . 93, 109
LIBOBJS, and Libtool. . . . . . . . . . . . . . . . . . . . . . . . . . . 60 multiple configurations, example. . . . . . . . . . . . . . . . . 7
LIBOBJS, example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 Multiple configure.ac files . . . . . . . . . . . . . . . . . . . . 25
LIBOBJS, special handling . . . . . . . . . . . . . . . . . . . . . . 66 Multiple lex lexers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
LIBRARIES primary, defined . . . . . . . . . . . . . . . . . . . . 55 multiple outputs, rules with . . . . . . . . . . . . . . . . . . . 126
libtool convenience libraries . . . . . . . . . . . . . . . . . . . . 58 Multiple yacc parsers . . . . . . . . . . . . . . . . . . . . . . . . . . 69
libtool libraries, conditional . . . . . . . . . . . . . . . . . . . . 57
libtool library, definition . . . . . . . . . . . . . . . . . . . . . . . 56
libtool modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 N
Libtool modules, default source example . . . . . . . . 66 Nested packages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
libtool, introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 56 Nesting packages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
LIBTOOLFLAGS and AM_LIBTOOLFLAGS . . . . . . . . . . 122 no-define . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42, 100
libtoolize and autoreconf . . . . . . . . . . . . . . . . . . . 61 no-dependencies . . . . . . . . . . . . . . . . . . . . . . . . . 77, 100
libtoolize, no longer run by automake . . . . . . . . 61 no-dist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Linking Fortran 77 with C and C++ . . . . . . . . . . . . 73 no-dist-gzip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
LISP primary, defined . . . . . . . . . . . . . . . . . . . . . . . . . . 84 no-exeext . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
LN_S example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 no-installinfo. . . . . . . . . . . . . . . . . . . . . . . . . . . 89, 101
local targets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 no-installinfo option . . . . . . . . . . . . . . . . . . . . . . . . 89
LTALLOCA, special handling . . . . . . . . . . . . . . . . . . . . . 60 no-installman . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90, 101
LTLIBOBJS and ansi2knr . . . . . . . . . . . . . . . . . . . . . . . 77 no-installman option . . . . . . . . . . . . . . . . . . . . . . . . . 90
LTLIBOBJS, special handling . . . . . . . . . . . . . . . . . . . . 60 no-texinfo.tex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
LTLIBRARIES primary, defined . . . . . . . . . . . . . . . . . . 56 nobase_ and dist_ or nodist_ . . . . . . . . . . . . . . . . . 49
ltmain.sh not found . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 nobase_ prefix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
nodist_ and nobase_ . . . . . . . . . . . . . . . . . . . . . . . . . . 49
nodist_ and notrans_ . . . . . . . . . . . . . . . . . . . . . . . . . 91
M ‘noinst_’ primary prefix, definition . . . . . . . . . . . . . 20
m4_include, distribution . . . . . . . . . . . . . . . . . . . . . . . 93 Non-GNU packages . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Macro search path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Non-standard targets . . . . . . . . . . . . . . . . . . . . . . . . . . 18
macro serial numbers . . . . . . . . . . . . . . . . . . . . . . . . . . 39 nostdinc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
Macros Automake recognizes . . . . . . . . . . . . . . . . . . . 30 notrans_ and dist_ or nodist_ . . . . . . . . . . . . . . . . 91
maintainer-clean-local . . . . . . . . . . . . . . . . . . . . . . 93 notrans_ prefix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
make check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
‘make clean’ support . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
‘make dist’ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 O
‘make distcheck’ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 OBJCFLAGS and AM_OBJCFLAGS . . . . . . . . . . . . . . . . . 122
‘make distclean’, diagnostic . . . . . . . . . . . . . . . . . . 120 Objective C support . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
‘make distcleancheck’ . . . . . . . . . . . . . . . . . . . . . . . . . 95 Objects in subdirectory . . . . . . . . . . . . . . . . . . . . . . . . 62
‘make distuninstallcheck’ . . . . . . . . . . . . . . . . . . . . 95 obsolete macros . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
‘make install’ support . . . . . . . . . . . . . . . . . . . . . . . . 91 optimized build, example . . . . . . . . . . . . . . . . . . . . . . . . 7
‘make installcheck’, testing --help Option, --warnings=category . . . . . . . . . . . . . . . . 103
and --version . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 Option, -Wcategory. . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Make rules, overriding . . . . . . . . . . . . . . . . . . . . . . . . . 18 Option, ansi2knr . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Make targets, overriding . . . . . . . . . . . . . . . . . . . . . . . 18 Option, check-news. . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Makefile fragment, including . . . . . . . . . . . . . . . . . 104 Option, color-tests . . . . . . . . . . . . . . . . . . . . . . . . . 100
Makefile.am, first line . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Option, cygnus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Makefile.am, Hello World . . . . . . . . . . . . . . . . . . . . . . 17 Option, dejagnu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Man page renaming, avoiding . . . . . . . . . . . . . . . . . . 90 Option, dist-bzip2. . . . . . . . . . . . . . . . . . . . . . . . . . . 100
MANS primary, defined . . . . . . . . . . . . . . . . . . . . . . . . . . 90 Option, dist-lzma . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
many outputs, rules with . . . . . . . . . . . . . . . . . . . . . 126 Option, dist-shar . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
mdate-sh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 Option, dist-tarZ . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
MinGW cross-compilation example . . . . . . . . . . . . . . 9 Option, dist-zip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Appendix B: Indices 165
Option, filename-length-max=99 . . . . . . . . . . . . . 100 Primary variable, MANS . . . . . . . . . . . . . . . . . . . . . . . . . 90
Option, foreign . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 Primary variable, PROGRAMS . . . . . . . . . . . . . . . . . . . . 19
Option, gnits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 Primary variable, PYTHON . . . . . . . . . . . . . . . . . . . . . . . 86
Option, gnu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 Primary variable, SCRIPTS . . . . . . . . . . . . . . . . . . . . . 79
Option, no-define . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 Primary variable, SOURCES . . . . . . . . . . . . . . . . . . . . . 51
Option, no-dependencies . . . . . . . . . . . . . . . . . . . . . 100 Primary variable, TEXINFOS . . . . . . . . . . . . . . . . . . . . 88
Option, no-dist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 prog_LDADD, defined. . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Option, no-dist-gzip . . . . . . . . . . . . . . . . . . . . . . . . 101 Programs, auxiliary . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Option, no-exeext . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 Programs, conditional . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Option, no-installinfo . . . . . . . . . . . . . . . . . . 89, 101 Programs, renaming during installation . . . . . . . . . 10
Option, no-installman . . . . . . . . . . . . . . . . . . . 90, 101 PROGRAMS primary variable . . . . . . . . . . . . . . . . . . . . . 19
Option, no-texinfo.tex . . . . . . . . . . . . . . . . . . . . . . 101 PROGRAMS, bindir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Option, nostdinc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 Proxy Makefile for third-party packages . . . . . . 112
Option, readme-alpha . . . . . . . . . . . . . . . . . . . . . . . . 101 ps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88, 109
Option, tar-pax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 ps-local . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Option, tar-ustar . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 PS output using Texinfo . . . . . . . . . . . . . . . . . . . . . . . 88
Option, tar-v7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 PYTHON primary, defined . . . . . . . . . . . . . . . . . . . . . . . . 86
Option, version . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Option, warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Options, aclocal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 R
Options, automake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Ratfor programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Options, std-options . . . . . . . . . . . . . . . . . . . . . . . . 101 read-only source tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Options, subdir-objects . . . . . . . . . . . . . . . . . . . . . 102 readme-alpha . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
Ordering flag variables . . . . . . . . . . . . . . . . . . . . . . . . 121 README-alpha . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Overriding make rules . . . . . . . . . . . . . . . . . . . . . . . . . . 18 rebuild rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98, 115
Overriding make targets . . . . . . . . . . . . . . . . . . . . . . . 18 Recognized macros by Automake . . . . . . . . . . . . . . . 30
Overriding make variables . . . . . . . . . . . . . . . . . . . . . . 18 Recursive operation of Automake. . . . . . . . . . . . . . . 18
overriding rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 recursive targets and third-party Makefiles . . . 110
overriding semantics . . . . . . . . . . . . . . . . . . . . . . . . . . 109 regex package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Renaming programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Reporting bugs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
P Requirements of Automake . . . . . . . . . . . . . . . . . . . . . 28
PACKAGE, directory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Requirements, Automake . . . . . . . . . . . . . . . . . . . . . . . . 1
PACKAGE, prevent definition . . . . . . . . . . . . . . . . . . . . . 42 Restrictions for JAVA . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Packages, nested . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 RFLAGS and AM_RFLAGS . . . . . . . . . . . . . . . . . . . . . . . . 122
Packages, preparation . . . . . . . . . . . . . . . . . . . . . . . . . . 11 rules with multiple outputs . . . . . . . . . . . . . . . . . . . 126
Parallel build trees . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 rules, conflicting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Path stripping, avoiding . . . . . . . . . . . . . . . . . . . . . . . . 49 rules, overriding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
pax format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 rx package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
pdf . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88, 109
pdf-local . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
PDF output using Texinfo . . . . . . . . . . . . . . . . . . . . . 88 S
Per-object flags, emulated . . . . . . . . . . . . . . . . . . . . . 125 Scanning configure.ac . . . . . . . . . . . . . . . . . . . . . . . . 28
per-target compilation flags, defined . . . . . . . . . . . . 64 SCRIPTS primary, defined . . . . . . . . . . . . . . . . . . . . . . . 79
pkgdatadir, defined. . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 SCRIPTS, installation directories . . . . . . . . . . . . . . . . 79
pkgincludedir, defined . . . . . . . . . . . . . . . . . . . . . . . . 20 Selecting the linker automatically . . . . . . . . . . . . . . 75
pkglibdir, defined . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 serial number and --install . . . . . . . . . . . . . . . . . . . 34
pkglibexecdir, defined . . . . . . . . . . . . . . . . . . . . . . . . 20 serial numbers in macros . . . . . . . . . . . . . . . . . . . . . . . 39
POSIX termios headers . . . . . . . . . . . . . . . . . . . . . . . . 44 Shared libraries, support for . . . . . . . . . . . . . . . . . . . . 55
Preparing distributions . . . . . . . . . . . . . . . . . . . . . . . . . 11 site.exp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Preprocessing Fortran 77 . . . . . . . . . . . . . . . . . . . . . . . 73 source tree and build tree . . . . . . . . . . . . . . . . . . . . . . . 6
Primary variable, DATA . . . . . . . . . . . . . . . . . . . . . . . . . 80 source tree, read-only . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Primary variable, defined . . . . . . . . . . . . . . . . . . . . . . 19 SOURCES primary, defined . . . . . . . . . . . . . . . . . . . . . . . 51
Primary variable, HEADERS . . . . . . . . . . . . . . . . . . . . . 80 Special Automake comment . . . . . . . . . . . . . . . . . . . . 19
Primary variable, JAVA . . . . . . . . . . . . . . . . . . . . . . . . . 85 Staged installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Primary variable, LIBRARIES . . . . . . . . . . . . . . . . . . . 55 std-options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
Primary variable, LISP . . . . . . . . . . . . . . . . . . . . . . . . . 84 Strictness, command line . . . . . . . . . . . . . . . . . . . . . . . 25
Primary variable, LTLIBRARIES . . . . . . . . . . . . . . . . . 56 Strictness, defined . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Appendix B: Indices 166
Strictness, foreign . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Transforming program names . . . . . . . . . . . . . . . . . . 10
Strictness, gnits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 trees, source vs. build . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Strictness, gnu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 true Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
su, before make install . . . . . . . . . . . . . . . . . . . . . . . . . 3
subdir-objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Subdirectories, building conditionally . . . . . . . . . . . 46 U
Subdirectories, configured conditionally . . . . . . . . 48 underquoted AC_DEFUN . . . . . . . . . . . . . . . . . . . . . . . . . 37
Subdirectories, not distributed . . . . . . . . . . . . . . . . . 48 Unified Parallel C support . . . . . . . . . . . . . . . . . . . . . 72
Subdirectory, objects in . . . . . . . . . . . . . . . . . . . . . . . . 62 Uniform naming scheme . . . . . . . . . . . . . . . . . . . . . . . . 19
SUBDIRS and AC_SUBST . . . . . . . . . . . . . . . . . . . . . . . . . 47 uninstall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4, 92, 109
SUBDIRS and AM_CONDITIONAL . . . . . . . . . . . . . . . . . . 47 uninstall-hook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
SUBDIRS, conditional . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 uninstall-local . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
SUBDIRS, explained . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Unpacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Subpackages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12, 49 UPCFLAGS and AM_UPCFLAGS . . . . . . . . . . . . . . . . . . . 122
suffix .la, defined . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 UPDATED Texinfo flag . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
suffix .lo, defined . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 UPDATED-MONTH Texinfo flag . . . . . . . . . . . . . . . . . . . . 88
SUFFIXES, adding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 Use Cases for the GNU Build System. . . . . . . . . . . . 2
Support for C++ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 user variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Support for Fortran 77 . . . . . . . . . . . . . . . . . . . . . . . . . 72 ustar format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Support for Fortran 9x . . . . . . . . . . . . . . . . . . . . . . . . . 75
Support for GNU Gettext . . . . . . . . . . . . . . . . . . . . . . 85
Support for Java . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 V
Support for Objective C . . . . . . . . . . . . . . . . . . . . . . . 71 v7 tar format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Support for Unified Parallel C . . . . . . . . . . . . . . . . . . 72 variables, conflicting . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Variables, overriding . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
variables, reserved for the user . . . . . . . . . . . . . . . . . 21
T version.m4, example . . . . . . . . . . . . . . . . . . . . . . . . . . 98
tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 version.sh, example . . . . . . . . . . . . . . . . . . . . . . . . . . 98
TAGS support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 VERSION Texinfo flag . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
tar formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 VERSION, prevent definition . . . . . . . . . . . . . . . . . . . . . 42
tar-pax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 versioned binaries, installing . . . . . . . . . . . . . . . . . . 110
tar-ustar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 VPATH builds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
tar-v7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Target, install-info . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Target, install-man . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
W
termios POSIX headers . . . . . . . . . . . . . . . . . . . . . . . . 44 wildcards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Test suites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Tests, expected failure . . . . . . . . . . . . . . . . . . . . . . . . . 97
Texinfo flag, EDITION . . . . . . . . . . . . . . . . . . . . . . . . . . 88
Texinfo flag, UPDATED . . . . . . . . . . . . . . . . . . . . . . . . . . 88
Y
Texinfo flag, UPDATED-MONTH. . . . . . . . . . . . . . . . . . . . 88 yacc, multiple parsers . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Texinfo flag, VERSION . . . . . . . . . . . . . . . . . . . . . . . . . . 88 YFLAGS and AM_YFLAGS . . . . . . . . . . . . . . . . . . . . . . . . 122
texinfo.tex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 ylwrap. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
TEXINFOS primary, defined . . . . . . . . . . . . . . . . . . . . . 88
third-party files and CVS . . . . . . . . . . . . . . . . . . . . . 117
Third-party packages, interfacing with . . . . . . . . 110 Z
timestamps and CVS . . . . . . . . . . . . . . . . . . . . . . . . . 115 zardoz example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
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Table of Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 An Introduction to the Autotools . . . . . . . . . . . . . . 1
2.1 Introducing the GNU Build System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2.2 Use Cases for the GNU Build System . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2.2.1 Basic Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2.2 Standard Makefile Targets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2.3 Standard Directory Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2.4 Standard Configuration Variables . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2.5 Overriding Default Configuration Setting with config.site . . 6
2.2.6 Parallel Build Trees (a.k.a. VPATH Builds) . . . . . . . . . . . . . . . . 6
2.2.7 Two-Part Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2.8 Cross-Compilation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2.9 Renaming Programs at Install Time . . . . . . . . . . . . . . . . . . . . . . 10
2.2.10 Building Binary Packages Using DESTDIR . . . . . . . . . . . . . . 10
2.2.11 Preparing Distributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.2.12 Automatic Dependency Tracking. . . . . . . . . . . . . . . . . . . . . . . . . 11
2.2.13 Nested Packages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.3 How Autotools Help . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.4 A Small Hello World . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.4.1 Creating amhello-1.0.tar.gz . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.4.2 amhello-1.0 Explained. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3 General ideas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.1 General Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.2 Strictness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.3 The Uniform Naming Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.4 How derived variables are named . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.5 Variables reserved for the user . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.6 Programs automake might require . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4 Some example packages. . . . . . . . . . . . . . . . . . . . . . . . 23
4.1 A simple example, start to finish . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
4.2 Building true and false . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
5 Creating a Makefile.in. . . . . . . . . . . . . . . . . . . . . . . . . 25
6 Scanning configure.ac . . . . . . . . . . . . . . . . . . . . . . . . . 28
6.1 Configuration requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
6.2 Other things Automake recognizes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6.3 Auto-generating aclocal.m4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
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6.3.1 aclocal options. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
6.3.2 Macro search path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
6.3.2.1 Modifying the macro search path: --acdir . . . . . . . . . . . 35
6.3.2.2 Modifying the macro search path: ‘-I dir’ . . . . . . . . . . . 36
6.3.2.3 Modifying the macro search path: dirlist . . . . . . . . . . . 36
6.3.3 Writing your own aclocal macros . . . . . . . . . . . . . . . . . . . . . . . . . . 37
6.3.4 Handling Local Macros . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
6.3.5 Serial Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
6.3.6 The Future of aclocal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
6.4 Autoconf macros supplied with Automake . . . . . . . . . . . . . . . . . . . . . 42
6.4.1 Public macros . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
6.4.2 Obsolete macros . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
6.4.3 Private macros . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
7 Directories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
7.1 Recursing subdirectories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
7.2 Conditional Subdirectories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
7.2.1 SUBDIRS vs. DIST_SUBDIRS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
7.2.2 Conditional subdirectories with AM_CONDITIONAL . . . . . . . . . . 47
7.2.3 Conditional Subdirectories with AC_SUBST . . . . . . . . . . . . . . . . . 47
7.2.4 Non-configured Subdirectories . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
7.3 An Alternative Approach to Subdirectories . . . . . . . . . . . . . . . . . . . . 49
7.4 Nesting Packages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
8 Building Programs and Libraries . . . . . . . . . . . . . 51
8.1 Building a program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
8.1.1 Defining program sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
8.1.2 Linking the program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
8.1.3 Conditional compilation of sources . . . . . . . . . . . . . . . . . . . . . . . . 53
8.1.3.1 Conditional compilation using _LDADD substitutions . . 53
8.1.3.2 Conditional compilation using Automake conditionals . . 53
8.1.4 Conditional compilation of programs . . . . . . . . . . . . . . . . . . . . . . 54
8.1.4.1 Conditional programs using configure substitutions . . 54
8.1.4.2 Conditional programs using Automake conditionals . . . 54
8.2 Building a library . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
8.3 Building a Shared Library . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
8.3.1 The Libtool Concept. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
8.3.2 Building Libtool Libraries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
8.3.3 Building Libtool Libraries Conditionally . . . . . . . . . . . . . . . . . . 57
8.3.4 Libtool Libraries with Conditional Sources . . . . . . . . . . . . . . . . 58
8.3.5 Libtool Convenience Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
8.3.6 Libtool Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
8.3.7 _LIBADD, _LDFLAGS, and _LIBTOOLFLAGS . . . . . . . . . . . . . . . . . . 60
8.3.8 LTLIBOBJS and LTALLOCA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
8.3.9 Common Issues Related to Libtool’s Use . . . . . . . . . . . . . . . . . . 60
8.3.9.1 ‘required file ‘./ltmain.sh’ not found’ . . . . . . . . . . 61
8.3.9.2 Objects ‘created with both libtool and without’ . . 61
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8.4 Program and Library Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
8.5 Default _SOURCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
8.6 Special handling for LIBOBJS and ALLOCA . . . . . . . . . . . . . . . . . . . . . . 66
8.7 Variables used when building a program . . . . . . . . . . . . . . . . . . . . . . . 68
8.8 Yacc and Lex support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
8.9 C++ Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
8.10 Objective C Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
8.11 Unified Parallel C Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
8.12 Assembly Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
8.13 Fortran 77 Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
8.13.1 Preprocessing Fortran 77 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
8.13.2 Compiling Fortran 77 Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
8.13.3 Mixing Fortran 77 With C and C++. . . . . . . . . . . . . . . . . . . . . 73
8.13.3.1 How the Linker is Chosen . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
8.14 Fortran 9x Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
8.14.1 Compiling Fortran 9x Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
8.15 Java Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
8.16 Support for Other Languages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
8.17 Automatic de-ANSI-fication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
8.18 Automatic dependency tracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
8.19 Support for executable extensions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
9 Other Derived Objects . . . . . . . . . . . . . . . . . . . . . . . . 78
9.1 Executable Scripts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
9.2 Header files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
9.3 Architecture-independent data files . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
9.4 Built sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
9.4.1 Built sources example. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
First try. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Using BUILT_SOURCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Recording dependencies manually . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Build bindir.h from configure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Build bindir.c, not bindir.h. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Which is best? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
10 Other GNU Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
10.1 Emacs Lisp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
10.2 Gettext . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
10.3 Libtool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
10.4 Java . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
10.5 Python . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
11 Building documentation . . . . . . . . . . . . . . . . . . . . . . 88
11.1 Texinfo. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
11.2 Man pages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
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12 What Gets Installed . . . . . . . . . . . . . . . . . . . . . . . . . . 91
12.1 Basics of installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
12.2 The two parts of install . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
12.3 Extending installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
12.4 Staged installs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
12.5 Rules for the user . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
13 What Gets Cleaned . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
14 What Goes in a Distribution . . . . . . . . . . . . . . . . 93
14.1 Basics of distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
14.2 Fine-grained distribution control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
14.3 The dist hook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
14.4 Checking the distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
14.5 The types of distributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
15 Support for test suites. . . . . . . . . . . . . . . . . . . . . . . . 97
15.1 Simple Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
15.2 DejaGnu Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
15.3 Install Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
16 Rebuilding Makefiles . . . . . . . . . . . . . . . . . . . . . . . . . 98
17 Changing Automake’s Behavior . . . . . . . . . . . . . 99
18 Miscellaneous Rules . . . . . . . . . . . . . . . . . . . . . . . . . 103
18.1 Interfacing to etags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
18.2 Handling new file extensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
18.3 Support for Multilibs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
19 Include . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
20 Conditionals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Portability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
21 The effect of --gnu and --gnits . . . . . . . . . . . . . 107
22 The effect of --cygnus . . . . . . . . . . . . . . . . . . . . . . . 108
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23 When Automake Isn’t Enough . . . . . . . . . . . . . 108
23.1 Extending Automake Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
23.2 Third-Party Makefiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
24 Distributing Makefile.ins . . . . . . . . . . . . . . . . . . . 113
25 Automake API versioning . . . . . . . . . . . . . . . . . . 113
26 Upgrading a Package to a Newer
Automake Version . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
27 Frequently Asked Questions
about Automake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
27.1 CVS and generated files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
27.1.1 Background: distributed generated files . . . . . . . . . . . . . . . . . 115
27.1.2 Background: CVS and timestamps. . . . . . . . . . . . . . . . . . . . . . 115
27.1.3 Living with CVS in Autoconfiscated projects . . . . . . . . . . . 115
27.1.4 Third-party files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
27.2 missing and AM_MAINTAINER_MODE . . . . . . . . . . . . . . . . . . . . . . . . . . 117
27.2.1 missing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
27.2.2 AM_MAINTAINER_MODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
27.3 Why doesn’t Automake support wildcards? . . . . . . . . . . . . . . . . . . 118
27.4 Limitations on file names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
27.5 Files left in build directory after distclean. . . . . . . . . . . . . . . . . . . . 120
27.6 Flag Variables Ordering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
27.6.1 Compile Flag Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
27.6.2 Other Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
27.7 Why are object files sometimes renamed? . . . . . . . . . . . . . . . . . . . . 124
27.8 Per-Object Flags Emulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
27.9 Handling Tools that Produce Many Outputs . . . . . . . . . . . . . . . . . 126
27.10 Installing to Hard-Coded Locations . . . . . . . . . . . . . . . . . . . . . . . . . 129
28 History of Automake . . . . . . . . . . . . . . . . . . . . . . . . 131
28.1 Timeline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
28.2 Dependency Tracking in Automake . . . . . . . . . . . . . . . . . . . . . . . . . . 143
28.2.1 First Take . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
Bugs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
Historical Note . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
28.2.2 Dependencies As Side Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
Bugs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
28.2.3 Dependencies for the User . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
Bugs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
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28.2.4 Techniques for Computing Dependencies . . . . . . . . . . . . . . . . 146
28.2.5 Recommendations for Tool Writers . . . . . . . . . . . . . . . . . . . . . 147
28.2.6 Future Directions for Automake’s Dependency Tracking . . 147
28.3 Release Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
Appendix A Copying This Manual . . . . . . . . . . . . 149
A.1 GNU Free Documentation License . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
Appendix B Indices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
B.1 Macro Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
B.2 Variable Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
B.3 General Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160