NM(1)NM(1) NAME nm - Print name list of object file(s) SYNOPSIS nm [options] [files] DESCRIPTION The nm command prints formatted listings of the symbol tables for each ELF file specified. A file can be a relocatable or absolute ELF object file, or it can be an archive. nm produces different output formats depending on options and the binary ABI. The differences are an attempt to preserve the operation of scripts that depend on nm. Anyone desiring consistent operation across different ABIs should use XPG4 format or Berkeley format. For old 32-bit-ABI objects the output format by default is the same as IRIX5.2 and 5.3 (something like AT&T System V Release 3 format). For new 32-bit-ABI objects the output format by is AT&T System V Release 4 format. For 64-bit objects the output format is by default in AT&T System V Release 4 format. If the _XPG environment variable is defined, nm operates in conformance with the X/Open XPG4 specifications (called XPG4 mode in this document). The XPG4 mode format follows the XPG4 standards. In XPG4 mode, nm output looks somewhat like nm -B (Berkeley style) output. When using AT&T System V Release 4 format, the following information will be printed for each symbol (an alternative, Berkeley (4.3BSD) format, is described later in this man page): Index The index of the symbol. (The index appears in brackets.) Value The value of the symbol is one of the following: a section offset for defined symbols in a relocatable file; alignment constraints for symbols whose section index is SHN_COMMON; a virtual address in executable and dynamic library files. Size The size in bytes of the associated object. Type A symbol is one of the following types: NOTYPE No type was specified. OBJECT A data object such as an array or variable. FUNC A function or other executable code. SECTION A section symbol FILE Name of the source file. Bind The symbol's binding attributes. LOCAL symbols have a scope limited to the object file containing their definition; GLOBAL symbols are visible to all object files being combined; and WEAK symbols are essentially global symbols with a lower precedence than GLOBAL. Other A name scope indicator for rld(). One of DEFAULT, INTERNAL, HIDDEN, PROTECTED. see STO_DEFAULT in sys/elf.h). Shndx Except for 3 special values, this is the section header table index in relation to which the symbol is defined. The following special values exist: ABS indicates the symbol's value will not change through relocation; COMMON indicates an unallocated block and the value provides alignment constraints; and UNDEF indicates an undefined symbol. Name The name of the symbol. The nm command supports the options listed below. The meaning of -o depends on if -A(AT&T) or -B is in effect when -o is encountered (the meaning depends on the relative ordering of the options). Examples: nm -Bo a.out nm -oB a.out In the first example, o is given the -B meaning, while in the second, it is given the -A (default) meaning. -A Use AT&T System V Release 4 format output. This is the default for new 32-bit ABI objects and 64bit ABI objects. In XPG4 mode, -A means write the full pathname of an object on each line. -B Use Berkeley (4.3BSD) format output. Overrides XPG4 mode. -b Print the value field in octal. -C Print decoded C++ names. -d Print the value field in decimal. This is the default value field radix for -A. -e Print externals and statics only. This option applies to 32- bit objects only and is ignored for 64-bit objects. -f Produce full output. (This option is obsolete and does nothing and will be removed in a future release). -g Print only globally-visible names. -h Do not print headers. -l Adds to the type field displayed in -p format by printing an asterisk (*) for weak names. Has no effect on other formats or on -B format. -n When used alone or with -A, sort symbols by name. By name is the default sort order for -B. When used with -B, sort all symbols by value. -o When used alone or with -A, print the value field in octal. When used with -B, prepend the filename to output line. This is useful for using grep to search through nm libraries. -p Produce easily parsable, terse output. -r Prepend the name of the object file or archive to each output line (Berkeley or XPG style) or name (ATT or default style). -u Print only undefined symbols. -v Sort symbols by value. -x Print value field in hexadecimal. This is the default value field radix for -B. -T Only applies to the 32-bit output format. Truncate long names, inserting an asterisk (*) as the last printed character. (Since symbol names have been moved to the last column, the problem of overflow is removed and this option is no longer necessary.) -V Print version information on standard error. -P In XPG4 mode, write information in a portable output format according to the XPG standard. -t format In XPG4 mode, write each numeric value in the specified format. The format should be one of the following: d The offset will be written in decimal. o The offset will be written in octal. x The offset will be written in hexadecimal. NM -B FORMAT For 32-bit objects, nm -B produces Berkeley output format with address or value field followed by a letter showing what section the symbol is in and the name of the symbol. Followed, if the symbol is a weak symbol, by (weak). The following section letters describe the information that nm generates: T External text. t Local text. D External initialized data. d Local initialized data. B External zeroed data. b Local zeroed data. A External absolute. a Local absolute. U External undefined. G External small initialized data. g Local small initialized data. I Init section (IRIX4 static shared library initialization code). S External small zeroed data. s Local small zeroed data. R External read only. r Local read only. C Common. E Small common. The following section letters were frequently emitted by nm in earlier releases but are now rarely emitted. N Nil storage class, compiler internal usage. V External small undefined. b Fortran based variable X Exception data P Procedure section (not a normal variable). F Fini section. o Non-GP data item (item not put in a small data area even though it may be small enough to fit). XPG4 mode In XPG4 mode the format is specified by the XPG4 standard. The output is sorted alphabetically by symbol name. The following information is output: Object Or library name, if -A is specified Name Symbol name Type Symbol type, which will be one of the following single characters (or one of the Berkeley format letters where non-conflicting with the following list). A Global absolute symbol a Local absolute symbol B External zeroed data b Local zeroed data D Global data symbol d Local data symbol T Global text symbol t Local text symbol U Undefined symbol Value The value of the symbol. Size The size of the symbol (0 if size not available). NOTES In some previous releases, the behavior of -rB was very different from -Br (in this case the r did nothing). This did not appear to be intentional and was certainly undocumented. Now they both do the same thing. SEE ALSO collide(1), elfdump(1), dwarfdump(1), stdump(1), odump(1), nlist(3e)