NAME
nm - list symbols from object files
SYNOPSIS
nm [-a│--debug-syms] [-g│--extern-only]
[-B] [-C│--demangle[=style]] [-D│--dynamic]
[-S│--print-size] [-s│--print-armap]
[-A│-o│--print-file-name][--special-syms]
[-n│-v│--numeric-sort] [-p│--no-sort]
[-r│--reverse-sort] [--size-sort] [-u│--undefined-only]
[-t radix│--radix=radix] [-P│--portability]
[--target=bfdname] [-fformat│--format=format]
[--defined-only] [-l│--line-numbers] [--no-demangle]
[-V│--version] [-X 32_64] [--help] [objfile...]
DESCRIPTION
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 local; if uppercase, the symbol is global (external).
"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" The symbol is an indirect reference to another symbol. This is
a GNU extension to the a.out object file format which is rarely
used.
"N" The symbol is a debugging symbol.
"R" The symbol is in a read only data section.
"S" The symbol is in an uninitialized data section for small
objects.
"T" The symbol is in the text (code) section.
"U" The symbol is undefined.
"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.
"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.
OPTIONS
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.
-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.
-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.
-S
--print-size
Print size, not the value, of defined symbols for the "bsd" output
format.
-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.
-r
--reverse-sort
Reverse the order of the sort (whether numeric or alphabetic); let
the last come first.
--size-sort
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.
--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 included in
the normal symbol lists. For example for ARM targets this option
would skip the mapping symbols used to mark transistions between
ARM code, THUMB code and data.
-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.
--target=bfdname
Specify an object code format other than your system’s default
format.
-u
--undefined-only
Display only undefined symbols (those external to each object
file).
--defined-only
Display only defined symbols for 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.
--help
Show a summary of the options to nm and exit.
SEE ALSO
ar(1), objdump(1), ranlib(1), and the Info entries for binutils.
COPYRIGHT
Copyright (c) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
2000, 2001, 2002, 2003, 2004 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 1.1 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’’.