nm - list symbols from object files
nm [-A|-o|--print-file-name]
[-a|--debug-syms]
[-B|--format=bsd] [-C|--demangle[=style]]
[-D|--dynamic]
[-fformat|--format=format]
[-g|--extern-only] [-h|--help]
[-l|--line-numbers] [--inlines]
[-n|-v|--numeric-sort]
[-P|--portability] [-p|--no-sort]
[-r|--reverse-sort] [-S|--print-size]
[-s|--print-armap] [-t
radix|--radix=radix]
[-u|--undefined-only] [-V|--version]
[-X 32_64] [--defined-only] [--no-demangle]
[--plugin name] [--size-sort] [--special-syms]
[--synthetic] [--with-symbol-versions]
[--target=bfdname]
[objfile...]
GNU nm lists the symbols from object files
objfile.... If no object files are listed as arguments, nm
assumes the file a.out.
For each symbol, nm shows:
- The symbol value, in the radix selected by options (see below), or
hexadecimal by default.
- The symbol type. At least the following types are used; others are, as
well, depending on the object file format. If lowercase, the symbol is
usually local; if uppercase, the symbol is global (external). There are
however a few lowercase symbols that are shown for special global symbols
("u",
"v" and
"w").
- "A"
- The symbol's value is absolute, and will not be changed by further
linking.
- "B"
- "b"
- The symbol is in the BSS data section. This section typically contains
zero-initialized or uninitialized data, although the exact behavior is
system dependent.
- "C"
- The symbol is common. Common symbols are uninitialized data. When linking,
multiple common symbols may appear with the same name. If the symbol is
defined anywhere, the common symbols are treated as undefined
references.
- "D"
- "d"
- The symbol is in the initialized data section.
- "G"
- "g"
- The symbol is in an initialized data section for small objects. Some
object file formats permit more efficient access to small data objects,
such as a global int variable as opposed to a large global array.
- "i"
- For PE format files this indicates that the symbol is in a section
specific to the implementation of DLLs. For ELF format files this
indicates that the symbol is an indirect function. This is a GNU extension
to the standard set of ELF symbol types. It indicates a symbol which if
referenced by a relocation does not evaluate to its address, but instead
must be invoked at runtime. The runtime execution will then return the
value to be used in the relocation.
- "I"
- The symbol is an indirect reference to another symbol.
- "N"
- The symbol is a debugging symbol.
- "p"
- The symbols is in a stack unwind section.
- "R"
- "r"
- The symbol is in a read only data section.
- "S"
- "s"
- The symbol is in an uninitialized or zero-initialized data section for
small objects.
- "T"
- "t"
- The symbol is in the text (code) section.
- "U"
- The symbol is undefined.
- "u"
- The symbol is a unique global symbol. This is a GNU extension to the
standard set of ELF symbol bindings. For such a symbol the dynamic linker
will make sure that in the entire process there is just one symbol with
this name and type in use.
- "V"
- "v"
- The symbol is a weak object. When a weak defined symbol is linked with a
normal defined symbol, the normal defined symbol is used with no error.
When a weak undefined symbol is linked and the symbol is not defined, the
value of the weak symbol becomes zero with no error. On some systems,
uppercase indicates that a default value has been specified.
- "W"
- "w"
- The symbol is a weak symbol that has not been specifically tagged as a
weak object symbol. When a weak defined symbol is linked with a normal
defined symbol, the normal defined symbol is used with no error. When a
weak undefined symbol is linked and the symbol is not defined, the value
of the symbol is determined in a system-specific manner without error. On
some systems, uppercase indicates that a default value has been
specified.
- "-"
- The symbol is a stabs symbol in an a.out object file. In this case, the
next values printed are the stabs other field, the stabs desc field, and
the stab type. Stabs symbols are used to hold debugging information.
- "?"
- The symbol type is unknown, or object file format specific.
- •
- The symbol name.
The long and short forms of options, shown here as alternatives,
are equivalent.
- -A
- -o
- --print-file-name
- Precede each symbol by the name of the input file (or archive member) in
which it was found, rather than identifying the input file once only,
before all of its symbols.
- -a
- --debug-syms
- Display all symbols, even debugger-only symbols; normally these are not
listed.
- -B
- The same as --format=bsd (for compatibility with the MIPS
nm).
- -C
- --demangle[=style]
- Decode (demangle) low-level symbol names into user-level names.
Besides removing any initial underscore prepended by the system, this
makes C++ function names readable. Different compilers have different
mangling styles. The optional demangling style argument can be used to
choose an appropriate demangling style for your compiler.
- --no-demangle
- Do not demangle low-level symbol names. This is the default.
- -D
- --dynamic
- Display the dynamic symbols rather than the normal symbols. This is only
meaningful for dynamic objects, such as certain types of shared
libraries.
- -f format
- --format=format
- Use the output format format, which can be
"bsd",
"sysv", or
"posix". The default is
"bsd". Only the first character of
format is significant; it can be either upper or lower case.
- -g
- --extern-only
- Display only external symbols.
- -h
- --help
- Show a summary of the options to nm and exit.
- -l
- --line-numbers
- For each symbol, use debugging information to try to find a filename and
line number. For a defined symbol, look for the line number of the address
of the symbol. For an undefined symbol, look for the line number of a
relocation entry which refers to the symbol. If line number information
can be found, print it after the other symbol information.
- --inlines
- When option -l is active, if the address belongs to a function that
was inlined, then this option causes the source information for all
enclosing scopes back to the first non-inlined function to be printed as
well. For example, if "main" inlines
"callee1" which inlines
"callee2", and address is from
"callee2", the source information for
"callee1" and
"main" will also be printed.
- -n
- -v
- --numeric-sort
- Sort symbols numerically by their addresses, rather than alphabetically by
their names.
- -p
- --no-sort
- Do not bother to sort the symbols in any order; print them in the order
encountered.
- -P
- --portability
- Use the POSIX.2 standard output format instead of the default format.
Equivalent to -f posix.
- -r
- --reverse-sort
- Reverse the order of the sort (whether numeric or alphabetic); let the
last come first.
- -S
- --print-size
- Print both value and size of defined symbols for the
"bsd" output style. This option has no
effect for object formats that do not record symbol sizes, unless
--size-sort is also used in which case a calculated size is
displayed.
- -s
- --print-armap
- When listing symbols from archive members, include the index: a mapping
(stored in the archive by ar or ranlib) of which modules
contain definitions for which names.
- -t radix
- --radix=radix
- Use radix as the radix for printing the symbol values. It must be
d for decimal, o for octal, or x for
hexadecimal.
- -u
- --undefined-only
- Display only undefined symbols (those external to each object file).
- -V
- --version
- Show the version number of nm and exit.
- -X
- This option is ignored for compatibility with the AIX version of
nm. It takes one parameter which must be the string 32_64.
The default mode of AIX nm corresponds to -X 32, which is
not supported by GNU nm.
- --defined-only
- Display only defined symbols for each object file.
- --plugin
name
- Load the plugin called name to add support for extra target types.
This option is only available if the toolchain has been built with plugin
support enabled.
If --plugin is not provided, but plugin support has
been enabled then nm iterates over the files in
${libdir}/bfd-plugins in alphabetic order and the first plugin
that claims the object in question is used.
Please note that this plugin search directory is not
the one used by ld's -plugin option. In order to make
nm use the linker plugin it must be copied into the
${libdir}/bfd-plugins directory. For GCC based compilations the
linker plugin is called liblto_plugin.so.0.0.0. For Clang based
compilations it is called LLVMgold.so. The GCC plugin is always
backwards compatible with earlier versions, so it is sufficient to just
copy the newest one.
- --size-sort
- Sort symbols by size. For ELF objects symbol sizes are read from the ELF,
for other object types the symbol sizes are computed as the difference
between the value of the symbol and the value of the symbol with the next
higher value. If the "bsd" output format
is used the size of the symbol is printed, rather than the value, and
-S must be used in order both size and value to be printed.
- --special-syms
- Display symbols which have a target-specific special meaning. These
symbols are usually used by the target for some special processing and are
not normally helpful when included in the normal symbol lists. For example
for ARM targets this option would skip the mapping symbols used to mark
transitions between ARM code, THUMB code and data.
- --synthetic
- Include synthetic symbols in the output. These are special symbols created
by the linker for various purposes. They are not shown by default since
they are not part of the binary's original source code.
- --with-symbol-versions
- Enables the display of symbol version information if any exists. The
version string is displayed as a suffix to the symbol name, preceded by an
@ character. For example foo@VER_1. If the version is the default
version to be used when resolving unversioned references to the symbol
then it is displayed as a suffix preceded by two @ characters. For example
foo@@VER_2.
- --target=bfdname
- Specify an object code format other than your system's default
format.
- @file
- Read command-line options from file. The options read are inserted
in place of the original @file option. If file does not
exist, or cannot be read, then the option will be treated literally, and
not removed.
Options in file are separated by whitespace. A
whitespace character may be included in an option by surrounding the
entire option in either single or double quotes. Any character
(including a backslash) may be included by prefixing the character to be
included with a backslash. The file may itself contain additional
@file options; any such options will be processed
recursively.
Copyright (c) 1991-2018 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".