nm

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

For each symbol, nm shows:

The symbol value, in the radix selected by the following options, 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 local; if uppercase, the symbol is global (external).

The symbol’s value is absolute, and will not be changed by further linking.

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 references. For more details on common symbols, see the discussion of –

warn-common

in Command Line Options in Using LD.

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

The symbol is an indirect reference to another symbol. This is a GNU extension to the

a.out

object file format which is rarely used.

The symbol is a debugging symbol.

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 weak. 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.

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; for more information, see the directives,

.stabd, .stabn, .stabs

in Assembler Directives in Using AS.

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 equivalent.

-A
-o
--print-file-name

Precede each symbol by the name of the input file (or archive element) in which it was found, rather than identifying the input file once only, before all of its symbols.

-a
--debug-syms

Display all symbols, even debugger-only symbols; normally these are not listed.

-B

The same as ‘

--format=bsd

’ (for compatibility with the MIPS

-C
--demangle

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. See

c++filt

for more information on demangling.

--no-demangle

Do not demangle low-level symbol names. This is the default.

-D
--dynamic

Display 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=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 be either upper or lower case.

-g
--extern-only

Display only external symbols.

-n
-v
--numeric-sort

Sort symbols numerically by their addresses, rather than alphabetically by their names.

-p
--no-sort

Do not bother to sort the symbols in any order; print them in the order encountered.

-P
--portability

Use the POSIX.2 standard output format instead of the default format. Equivalent to ‘

-f

posix

’.

-s
--print-armap

When listing symbols from archive members, include the index: a mapping (stored in the archive by

ranlib

) of which modules contain definitions for which names.

-r
--reverse-sort

Reverse the order of the sort (whether numeric or alphabetic); let the last come first.

--size-sort

Sort symbols by

size

is computed as the difference between the value of the symbol and the value of the symbol with the next higher value. The size of the symbol is printed, rather than the value.

-t radix
--radix=radix

Use radix as the radix for printing the symbol values. It must be ‘

’ for decimal, ‘

’ for octal, or ‘

’ for hexadecimal.

--target=bfdname

Specify an object code format other than your system’s default format. See Target Selection for more information.

-u
--undefined-only

Display only undefined symbols (those external to each object file).

--defined-only

Display only defined symbols for each object file.

-V
--version

Show the version number of

and exit.

--help

Show a summary of the options to

and exit.