There are three possibilities to configure the findlib library:
Build time:
Before findlib is compiled, a "configure"
script is invoked to figure out the settings that are most likely to work on
the system. Most settings are simply entered into text files and can easily be
changed after installation. The following properties cannot be changed later
because they are compiled into the resulting binaries:
The default location of the configuration file
findlib.conf. However, you can set a different location by the environment
variable OCAMLFIND_CONF.
Whether the installed O'Caml version supports autolinking
or not.
Configuration file findlib.conf:
An initial version of this file is generated by the
configure script, but you are free to modify it later. Most important, this
file contains the system-wide search path used to look up packages, and the
default location where to install new packages.
All files with the suffix ".conf" found in the directory
findlib.conf.d are also scanned for parameters.
Environment variables:
The settings of findlib.conf can be overridden by
environment variables.
Last but not least, several settings can also be passed as
command-line options, or by invoking the function Findlib.init.
The directory containing findlib.conf is determined at build time
(by running the configure script), the fallback default is /usr/local/etc.
You can set a different location by changing the environment variable
OCAMLFIND_CONF which must contain the absolute path of findlib.conf.
The file has the same syntax as META, i.e. it consists of a number
of lines with the format
variable
= "
value
"
Here is the list of allowed variables:
path
The search path for META files/package directories. The
variable enumerates directories which are separated by colons (Windows:
semicolons), and these directories are tried in turn to find a certain
package. More exactly, if d is such a directory and p the searched package,
the search algorithm will first check whether d/p/META exists. In this case,
this META file is taken, and d/p is the package directory. Second, the
algorithm tries d/META.p, but the package directory must be specified in this
META.p file by a directory directive.
Note that the first found META file is taken, so the order of the
directories in the search path counts.
This variable is required.
Example:
path = "/usr/local/lib/ocaml/site-lib:/usr/lib/ocaml/site-lib"
destdir
This variable determines the location where ocamlfind
install puts the packages by default: If d is this directory, and p the
package to install, a new subdirectory d/p will be created containing all the
files of the package.
Example:
destdir = "/usr/local/lib/ocaml/site-lib"
This variable is required.
metadir
If set, the command ocamlfind install will put the META
files of packages into this directory (files are named META.p where p=package
name); otherwise the META files are put into the package directories like any
other file.
Example:
metadir = "/var/lib/findlib/metaregistry"
This variable is optional. It is not used by default.
ocamlc, ocamlopt, ocamlcp, ocamlmktop, ocamldoc,
ocamldep, ocamlbrowser
If you want to call other executables than
"ocamlc", "ocamlopt", "ocamlcp",
"ocamlmktop", "ocamldoc", "ocamldep", and
"ocamlbrowser", you can set the names of the executables here. The
command ocamlfind looks into these four variables to determine the names of
the compilers to call.
Example:
ocamlc = "ocamlc.opt"
ocamlopt = "ocamlopt.opt"
ocamlcp = "ocamlcp.opt"
ocamlmktop = "ocamlmktop.opt"
This variable is optional. It is not used by default.
stdlib
This variable determines the location of the standard
library. This must be the same directory for which the O'Caml compilers are
configured.
This variable is optional. It is not recommend to set this
variable unless you know what you are doing!
ldconf
This variable determines the location of the ld.conf
file. This must be the same file the O'Caml compilers read in; it is updated
by ocamlfind when installing and removing packages. You can set this variable
to the special value "ignore" to disable the automatic modification
of the ld.conf file.
If not set, the ld.conf file is assumed to reside in the O'Caml
standard library directory.
This variable is optional. It is not recommended to set this
variable unless you know what you are doing!
Toolchains: It is possible to have variants of the original
configuration. These variants are called "toolchains" because they
are intended to select different compilers, e.g. patched compilers. In order
to set a variable for a certain toolchain, use the syntax
variable
(
toolchain
) = "
value
"
For example:
ocamlc(mypatch) = "ocamlc-mypatch"
When the toolchain "mypatch" is selected, this compiler will be used
instead of the standard one.
In order to switch to a certain toolchain, use the -toolchain
option of ocamlfind.
A number of environment variables modifies the behaviour of
findlib/ocamlfind:
OCAMLFIND_CONF
This variable overrides the location of the configuration
file findlib.conf. It must contain the absolute path name of this file.
OCAMLFIND_TOOLCHAIN
This variable sets the currently selected toolchain when
a -toolchain option is not passed on the command line.
OCAMLPATH
This variable may contain an additional search path for
package directories. It is treated as if the directories were prepended to the
configuration variable path.
OCAMLFIND_DESTDIR
This variable overrides the configuration variable
destdir.
OCAMLFIND_METADIR
This variable overrides the configuration variable
metadir.
OCAMLFIND_COMMANDS
This variable overrides the configuration variables
ocamlc, ocamlopt, ocamlcp, ocamlmktop, ocamldoc, ocamldep, and/or
ocamlbrowser. Its value must conform to the syntax
ocamlc=
name
ocamlopt=
name
ocamlcp=
name
ocamlmktop=
name
ocamldoc=
name
ocamldep=
name
ocamlbrowser=
name
Example:
ocamlc=ocamlc-3.00 ocamlopt=ocamlopt-3.00 ocamlcp=ocamlcp-3.00 ocamlmktop=ocamlmktop-3.00
CAMLLIB or OCAMLLIB
This variable overrides the configuration variable
stdlib.
OCAMLFIND_LDCONF
This variable overrides the configuration variable
ldconf.
OCAMLFIND_IGNORE_DUPS_IN
This variable instructs findlib not to emit warnings that
packages or module occur several times. The variable must be set to the
directory where the packages reside that are to be ignored for this warning.