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).
A
The symbols
value is absolute, and will not be changed by further linking.
B
The symbol is
in the uninitialized data section (known as BSS).
C
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.
D
The symbol is
in the initialized data section.
G
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.
I
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.
N
The symbol is
a debugging symbol.
R
The symbol is
in a read only data section.
S
The symbol is
in an uninitialized data section for small objects.
T
The symbol is
in the text (code) section.
U
The symbol is
undefined.
W
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 nm).
-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 ar
or 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.
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 d
for decimal, o
for octal, or x
for hexadecimal.
--target=bfdname
Specify an object
code format other than your systems 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.
