nm [-A|-o|--print-file-name] [-a|--debug-syms]
[-s|--print-armap] [-t radix|--radix=radix]
[-X 32_64] [--defined-only] [--no-demangle]
[--plugin name] [--size-sort] [--special-syms]
gnu nm lists the symbols from object files objfile....
If no object files are listed as arguments, nm assumes the file
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
- The symbol's value is absolute, and will not be changed by further
- The symbol is in the uninitialized data section (known as BSS).
- 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
For more details on common symbols, see the discussion of
–warn-common in Linker options.
- The symbol is in the initialized data section.
- 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.
- 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.
- The symbol is an indirect reference to another symbol.
- The symbol is a debugging symbol.
- The symbols is in a stack unwind section.
- The symbol is in a read only data section.
- The symbol is in an uninitialized data section for small objects.
- The symbol is in the text (code) section.
- The symbol is undefined.
- 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.
- 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.
- 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.
- 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
- 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 compiler. See c++filt,
for more information on demangling.
- 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
- -f format
- Use the output format format, which can be
posix. The default is
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
- 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 file).
- Show the version number of nm and exit.
- 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 code.
- Specify an object code format other than your system's default format.
See Target Selection, for more information.