nm(1)
NM(1) GNU Development Tools NM(1)
NAME
nm - list symbols from object files
SYNOPSIS
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...]
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:
o The symbol value, in the radix selected by options (see
below), or hexadecimal by default.
o 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 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"
"d" The symbol is in the initialized data section.
binutils-2.30 Last change: 2018-01-27 1
NM(1) GNU Development Tools NM(1)
"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 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.
binutils-2.30 Last change: 2018-01-27 2
NM(1) GNU Development Tools NM(1)
"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.
o 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.
binutils-2.30 Last change: 2018-01-27 3
NM(1) GNU Development Tools NM(1)
--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
binutils-2.30 Last change: 2018-01-27 4
NM(1) GNU Development Tools NM(1)
--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
binutils-2.30 Last change: 2018-01-27 5
NM(1) GNU Development Tools NM(1)
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, preceeded 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 preceeded
by two @ characters. For example foo@@VER_2.
binutils-2.30 Last change: 2018-01-27 6
NM(1) GNU Development Tools NM(1)
--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.
SEE ALSO
ar(1), objdump(1), ranlib(1), and the Info entries for
binutils.
COPYRIGHT
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".
binutils-2.30 Last change: 2018-01-27 7
Man(1) output converted with
man2html