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] [--with-symbol-versions] [--target=bfdname] [objfile…]
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:
u, v and w).
AThe symbol’s value is absolute, and will not be changed by further linking.
BbThe symbol is in the uninitialized data section (known as BSS).
CThe 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. For more details on common symbols, see the discussion of –warn-common in Linker options in The GNU linker.
DdThe symbol is in the initialized data section.
GgThe 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.
iFor 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.
IThe symbol is an indirect reference to another symbol.
NThe symbol is a debugging symbol.
pThe symbols is in a stack unwind section.
RrThe symbol is in a read only data section.
SsThe symbol is in an uninitialized data section for small objects.
TtThe symbol is in the text (code) section.
UThe symbol is undefined.
uThe 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.
VvThe 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.
WwThe 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 long and short forms of options, shown here as alternatives, are equivalent.
-A-o--print-file-namePrecede 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-symsDisplay all symbols, even debugger-only symbols; normally these are not listed.
-BThe 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. See c++filt, for more information on demangling.
--no-demangleDo not demangle low-level symbol names. This is the default.
-D--dynamicDisplay 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=formatUse 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-onlyDisplay only external symbols.
-h--helpShow a summary of the options to nm and exit.
-l--line-numbersFor 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.
-n-v--numeric-sortSort symbols numerically by their addresses, rather than alphabetically by their names.
-p--no-sortDo not bother to sort the symbols in any order; print them in the order encountered.
-P--portabilityUse the POSIX.2 standard output format instead of the default format. Equivalent to ‘-f posix’.
-r--reverse-sortReverse the order of the sort (whether numeric or alphabetic); let the last come first.
-S--print-sizePrint 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-armapWhen 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=radixUse radix as the radix for printing the symbol values. It must be ‘d’ for decimal, ‘o’ for octal, or ‘x’ for hexadecimal.
-u--undefined-onlyDisplay only undefined symbols (those external to each object file).
-V--versionShow the version number of nm and exit.
-XThis 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-onlyDisplay only defined symbols for each object file.
--plugin nameLoad 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.
--size-sortSort 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-symsDisplay 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.
--syntheticInclude 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.
--with-symbol-versionsEnables 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’.
--target=bfdnameSpecify an object code format other than your system’s default format. See Target Selection, for more information.