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Section: GNU Development Tools (1)
Updated: 2017-09-21


nm - list symbols from object files 


nm [-a|--debug-syms]
   [-g|--extern-only][--plugin name]
   [-B] [-C|--demangle[=style]] [-D|--dynamic]
   [-S|--print-size] [-s|--print-armap]
   [-n|-v|--numeric-sort] [-p|--no-sort]
   [-r|--reverse-sort] [--size-sort] [-u|--undefined-only]
   [-t radix|--radix=radix] [-P|--portability]
   [--target=bfdname] [-fformat|--format=format]
   [--defined-only] [-l|--line-numbers] [--no-demangle]
   [-V|--version] [-X 32_64] [--help]  [objfile...] 


GNU nm lists the symbols from object files objfile....If no object files are listed as arguments, nm assumes the filea.out.

For each symbol, nm shows:

The symbol value, in the radix selected by options (see below), orhexadecimal by default.
The symbol type. At least the following types are used; others are, aswell, depending on the object file format. If lowercase, the symbol isusually local; if uppercase, the symbol is global (external). Thereare however a few lowercase symbols that are shown for special globalsymbols ("u", "v" and "w").
The symbol's value is absolute, and will not be changed by furtherlinking.
The symbol is in the uninitialized data section (known as BSS).
The symbol is common. Common symbols are uninitialized data. Whenlinking, multiple common symbols may appear with the same name. If thesymbol is defined anywhere, the common symbols are treated as undefinedreferences.
The symbol is in the initialized data section.
The symbol is in an initialized data section for small objects. Someobject 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 sectionspecific to the implementation of DLLs. For ELF format files thisindicates that the symbol is an indirect function. This is a GNUextension to the standard set of ELF symbol types. It indicates asymbol which if referenced by a relocation does not evaluate to itsaddress, but instead must be invoked at runtime. The runtimeexecution will then return the value to be used in the relocation.
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 thestandard set of ELF symbol bindings. For such a symbol the dynamic linkerwill make sure that in the entire process there is just one symbol withthis name and type in use.
The symbol is a weak object. When a weak defined symbol is linked witha 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 somesystems, uppercase indicates that a default value has been specified.
The symbol is a weak symbol that has not been specifically tagged as aweak object symbol. When a weak defined symbol is linked with a normaldefined 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 withouterror. On some systems, uppercase indicates that a default value has beenspecified.
The symbol is a stabs symbol in an a.out object file. In this case, thenext values printed are the stabs other field, the stabs desc field, andthe 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, areequivalent.
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 notlisted.
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, thismakes C++ function names readable. Different compilers have differentmangling styles. The optional demangling style argument can be used tochoose an appropriate demangling style for your compiler.
Do not demangle low-level symbol names. This is the default.
Display the dynamic symbols rather than the normal symbols. This isonly meaningful for dynamic objects, such as certain types of sharedlibraries.
-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 beeither upper or lower case.
Display only external symbols.
--plugin name
Load the plugin called name to add support for extra targettypes. This option is only available if the toolchain has been builtwith plugin support enabled.
For each symbol, use debugging information to try to find a filename andline number. For a defined symbol, look for the line number of theaddress of the symbol. For an undefined symbol, look for the linenumber of a relocation entry which refers to the symbol. If line numberinformation can be found, print it after the other symbol information.
Sort symbols numerically by their addresses, rather than alphabeticallyby their names.
Do not bother to sort the symbols in any order; print them in the orderencountered.
Use the POSIX.2 standard output format instead of the default format.Equivalent to -f posix.
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 symbolsizes, unless --size-sort is also used in which case acalculated size is displayed.
When listing symbols from archive members, include the index: a mapping(stored in the archive by ar or ranlib) of which modulescontain definitions for which names.
Reverse the order of the sort (whether numeric or alphabetic); let thelast come first.
Sort symbols by size. The size is computed as the difference betweenthe value of the symbol and the value of the symbol with the next highervalue. If the "bsd" output format is used the size of the symbolis printed, rather than the value, and -S must be used in orderboth size and value to be printed.
Display symbols which have a target-specific special meaning. Thesesymbols are usually used by the target for some special processing andare not normally helpful when included included in the normal symbollists. For example for ARM targets this option would skip the mappingsymbols used to mark transitions between ARM code, THUMB code anddata.
-t radix
Use radix as the radix for printing the symbol values. It must bed for decimal, o for octal, or x for hexadecimal.
Specify an object code format other than your system's default format.
Display only undefined symbols (those external to each object file).
Display only defined symbols for each object file.
Show the version number of nm and exit.
This option is ignored for compatibility with the AIX version ofnm. It takes one parameter which must be the string32_64. The default mode of AIX nm correspondsto -X 32, which is not supported by GNU nm.
Show a summary of the options to nm and exit.
Read command-line options from file. The options read areinserted in place of the original @file option. If filedoes not exist, or cannot be read, then the option will be treatedliterally, and not removed.

Options in file are separated by whitespace. A whitespacecharacter may be included in an option by surrounding the entireoption in either single or double quotes. Any character (including abackslash) may be included by prefixing the character to be includedwith 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. 


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Permission is granted to copy, distribute and/or modify this documentunder the terms of the GNU Free Documentation License, Version 1.3or any later version published by the Free Software Foundation;with no Invariant Sections, with no Front-Cover Texts, and with noBack-Cover Texts. A copy of the license is included in thesection entitled ``GNU Free Documentation License''.




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