x86_64-linux-gnu-nm Man page

NM(1) GNU Development Tools NM(1)


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] [-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] [–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” The symbol is in the uninitialized data section (known as BSS).

“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” The symbol is in the initialized data section.

“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” The symbol is in a read only data section.

“s” The symbol is in an uninitialized data section for small

“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” 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” 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

“-” 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

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.

Display all symbols, even debugger-only symbols; normally these are
not listed.

-B The same as –format=bsd (for compatibility with the MIPS nm).

–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

Do not demangle low-level symbol names. This is the default.

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
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.

Display only external symbols.

Show a summary of the options to nm and exit.

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.

Sort symbols numerically by their addresses, rather than
alphabetically by their names.

Do not bother to sort the symbols in any order; print them in the
order encountered.

Use the POSIX.2 standard output format instead of the default
format. Equivalent to -f posix.

Reverse the order of the sort (whether numeric or alphabetic); let
the last come first.

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.

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
Use radix as the radix for printing the symbol values. It must be
d for decimal, o for octal, or x for hexadecimal.

Display only undefined symbols (those external to each object

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.

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.

Sort symbols by size. The size is 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.

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.

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

Specify an object code format other than your system’s default

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

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.


ar, objdump, ranlib, and the Info entries for binutils.


Copyright (c) 1991-2015 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”.

binutils-2.26.1 2016-06-29 NM(1)