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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | SEE ALSO | COPYRIGHT | COLOPHON |
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] [--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 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.
"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.
"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.
-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.
--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.
--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.
ar(1), objdump(1), ranlib(1), and the Info entries for binutils.
Copyright (c) 1991-2017 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".
This page is part of the binutils (a collection of tools for working
with executable binaries) project. Information about the project can
be found at ⟨http://www.gnu.org/software/binutils/⟩. If you have a
bug report for this manual page, see
⟨http://sourceware.org/bugzilla/enter_bug.cgi?product=binutils⟩. This
page was obtained from the tarball binutils-2.28.tar.gz fetched from
⟨https://ftp.gnu.org/gnu/binutils/⟩ on 2017-07-05. If you discover
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you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a mail
to man-pages@man7.org
binutils-2.28 2017-03-02 NM(1)
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