Manual Pages  — NM

nm – display symbolic information in object files

SYNOPSIS DESCRIPTION OUTPUT FORMAT EXIT STATUS SEE ALSO AUTHORS

nm [--debug-syms] [--defined-only] [--demangle [=style]] [--dynamic] [--extern-only] [--help] [--line-numbers] [--no-demangle] [--no-sort] [--numeric-sort] [--print-armap] [--print-file-name] [--print-size] [--radix= format] [--reverse-sort] [--size-sort] [--undefined-only] [--version] [-A] [-B] [-C [style]] [-D] [-P] [-V] [-a] [-e] [-g] [-h] [-l] [-n] [-o] [-p] [-r] [-S] [-s] [-t format] [-u] [-x] file ...

The nm utility displays symbolic information in the object files, executables, and object library files named by its arguments. Lack of symbolic information in an otherwise valid input file, is not considered to be an error. If no files are specified on the command line, nm will attempt to read a.out.

The nm utility recognizes the following options:

--debug-syms
	Display all symbols, including debugger-only symbols.
--defined-only
	Display only defined symbols.
--demangle [=style]
	Decode (demangle) low-level symbol names into human-readable names. Supported values for argument style are 'auto', 'gnu-v2', 'gnu-v3' and 'arm.' If argument style is not specified, it is taken to be 'auto'.
--dynamic
	Only display dynamic symbols. This option is only meaningful for shared libraries.
--extern-only
	Only display information about global (external) symbols.
--help
	Display a help message and exit.
--format -= format
	Display output in the format specified by argument format. Supported values for the format argument are 'bsd', 'sysv', and 'posix'. The default output format is 'bsd'.
--line-numbers
	Display the filename and line number associated a symbol using any debugging information present in the input file. For defined symbols, look up the line number associated with the address of the symbol. For undefined symbols, look up the line number associated with a relocation entry that refers to the symbol. If line number information can be determined, it is displayed after other symbol information.
--no-demangle
	Do not demangle symbol names (default).
--no-sort
	Do not sort symbols.
--numeric-sort
	Sort symbols numerically by address instead of alphabetically by name.
--print-armap
	For ar(1) archives, include the index of the archive's members.
--print-file-name
	Write the full pathname or library name of an object on each line, before the rest of the information for a symbol. If this option is not specified, nm will only identify an input file once, before its symbols are listed.
--print-size
	Print the size of each symbol instead of its value.
--radix -= radix
	Print numeric values using the specified radix. Supported values for argument radix are 'd' for decimal, 'o' for octal, and 'x' for hexadecimal.
--reverse-sort
	Reverse the order of the sort.
--size-sort
	Sort symbols by size instead of alphabetically by name.
--undefined-only
	Display only undefined symbols.
--version
	Display the version identifier for nm and exit.
-A	Equivalent to specifying option --print-file-name.
-B	Equivalent to specifying option --format= bsd.
-C [style]
	Equivalent to specifying option --demangle [=style].
-D	Equivalent to specifying option --dynamic.
-F format
	Equivalent to specifying option --format -= format.
-P	Equivalent to specifying option --format -= posix.
-S	Equivalent to specifying option --print-size.
-V	Equivalent to specifying option --version.
-a	Equivalent to specifying option --debug-syms.
-e	Only display information for global and static symbols.
-f	Produce full output (default).
-g	Equivalent to specifying option --extern-only.
-h	Equivalent to specifying option --help.
-l	Equivalent to specifying option --line-numbers.
-n	Equivalent to specifying option --numeric-sort.
-o	If POSIX output was specified using the -F posix or -P options, this option is equivalent to specifying --radix -= 'o'. If POSIX output was not specified, this option acts as a synonym for the --print-file-name option.
-p	Equivalent to specifying option --no-sort.
-v	Equivalent to option -n.
-r	Equivalent to specifying option --reverse-sort
-s	Equivalent to specifying option --print-armap.
-t radix
	Equivalent to specifying option --radix= radix.
-u	Equivalent to specifying option --undefined-only.
-x	Write numeric values in hexadecimal (equivalent to -t x).

The nm utility can present its information in a number of formats, numeric radices and sort orders. By default nm uses BSD style output, a hexadecimal radix, without output sorted alphabetically by name and without demangling of names.

For each symbol listed, nm presents the following information:

• The library or object name, if options -A or --print-file-name were specified.
• The symbol name.
• The type of the symbol denoted by a single character as below:

  A	A global, absolute symbol.
  B	A global "bss" (uninitialized data) symbol.
  C	A "common" symbol, representing uninitialized data.
  D	A global symbol naming initialized data.
  N	A debugger symbol.
  R	A read-only data symbol.
  T	A global text symbol.
  U	An undefined symbol.
  V	A weak object.
  W	A weak reference.
  a	A local absolute symbol.
  b	A local "bss" (uninitialized data) symbol.
  d	A local data symbol.
  r	A local read-only data symbol.
  t	A local text symbol.
  v	A weak object that is undefined.
  w	A weak symbol that is undefined.
  ?	None of the above.

• The value of the symbol.
• The size of the symbol if applicable.
• Line number information, if available and if options -l or --line-numbers were specified.

The utility exits 0 on success, and >0 if an error occurs.

The nm utility and this manual page were written by Hyogeol Lee <Mt hyogeollee@gmail.com>.