nm(1) — Linux manual page


NM(1)                       GNU Development Tools                      NM(1)

NAME         top

       nm - list symbols from object files

SYNOPSIS         top

       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]
          [-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]

DESCRIPTION         top

       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 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" 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.

           "n" The symbol is in the read-only data section.

           "p" The symbol is in a stack unwind section.

           "r" The symbol is in a read only data section.

           "s" The symbol is in an uninitialized or zero-initialized data
               section for small objects.

           "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 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         top

       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).

           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.

           Enables or disables a limit on the amount of recursion performed
           whilst demangling strings.  Since the name mangling formats allow
           for an inifinite level of recursion it is possible to create
           strings whose decoding will exhaust the amount of stack space
           available on the host machine, triggering a memory fault.  The
           limit tries to prevent this from happening by restricting
           recursion to 2048 levels of nesting.

           The default is for this limit to be enabled, but disabling it may
           be necessary in order to demangle truly complicated names.  Note
           however that if the recursion limit is disabled then stack
           exhaustion is possible and any bug reports about such an event
           will be rejected.

           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.

           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.

           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.

           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.

           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

           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 code.

           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.

           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 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         top

       ar(1), objdump(1), ranlib(1), and the Info entries for binutils.

COPYRIGHT         top

       Copyright (c) 1991-2020 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".

COLOPHON         top

       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
       This page was obtained from the tarball binutils-2.35.1.tar.gz
       fetched from ⟨https://ftp.gnu.org/gnu/binutils/⟩ on 2020-11-01.  If
       you discover any rendering problems in this HTML version of the page,
       or you believe there is a better or more up-to-date source for the
       page, or 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-2.35.1                  2020-09-19                            NM(1)

Pages that refer to this page: ar(1)ld(1)objdump(1)ranlib(1)strings(1)elf(5)