nm manpage

Search topic Section

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] [--target=bfdname]

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

	   "s" The symbol is in an uninitialized data section for small

	   "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

	   "-" 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.

       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.

	   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.

	   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.

	   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.

	   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

	   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

	   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) 1991-2016 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-2.27			  2016-08-03				 NM(1)