nm

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]
          [--ifunc-chars=CHARS]
          [-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]
          [--no-recurse-limit|--recurse-limit]]
          [--size-sort] [--special-syms]
          [--synthetic] [--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:

       •   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 BSS data section.  This section typically
               contains zero-initialized or uninitialized data, although the
               exact behavior is system dependent.

           "C"
           "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.  The lower case c character is
               used when the symbol is in a special section for small commons.

           "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.

               Note - the actual symbols display for GNU indirect symbols is
               controlled by the --ifunc-chars command line option.  If this
               option has been provided then the first character in the string
               will be used for global indirect function symbols.  If the string
               contains a second character then that will be used for local
               indirect function symbols.

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

           "S"
           "s" The symbol is in an uninitialized or zero-initialized 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.  If a symbol has version information associated with
           it, then the version information is displayed as well.  If the
           versioned symbol is undefined or hidden from linker, the version
           string is displayed as a suffix to the symbol name, preceded 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 preceded by two @
           characters.  For example foo@@VER_2.

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.

       --recurse-limit
       --no-recurse-limit
       --recursion-limit
       --no-recursion-limit
           Enables or disables a limit on the amount of recursion performed
           whilst demangling strings.  Since the name mangling formats allow for
           an infinite 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.

       -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.

       --ifunc-chars=CHARS
           When display GNU indirect function symbols nm will default to using
           the "i" character for both local indirect functions and global
           indirect functions.  The --ifunc-chars option allows the user to
           specify a string containing one or two characters. The first
           character will be used for global indirect function symbols and the
           second character, if present, will be used for local indirect
           function 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.

       --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
       --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.

           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.

       --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) 1991-2021 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-2.36.1                    2021-02-06                              NM(1)