NAME
nm - list symbols from object files
SYNOPSIS
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] [
--target=bfdname]
[
objfile...]
DESCRIPTION
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:
- •
- The symbol value, in the radix selected by options (see
below), 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 usually local; if uppercase, the symbol is global
(external). There are however a few lowercase symbols that are shown for
special global symbols ("u", "v" and
"w").
- "A"
- The symbol's value is absolute, and will not be changed by
further linking.
- "B"
- "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.
- "D"
- "d"
- The symbol is in the initialized data section.
- "G"
- "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"
- For 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.
- "I"
- The symbol is an indirect reference to another symbol.
- "N"
- The symbol is a debugging symbol.
- "p"
- The symbols is in a stack unwind section.
- "R"
- "r"
- The symbol is in a read only data section.
- "S"
- "s"
- The symbol is in an uninitialized data section for small
objects.
- "T"
- "t"
- The symbol is in the text (code) section.
- "U"
- The symbol is undefined.
- "u"
- The 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.
- "V"
- "v"
- The 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.
- "W"
- "w"
- The 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 symbol name.
OPTIONS
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 member) 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[=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.
- --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.
- -h
- --help
- Show a summary of the options to nm and exit.
- -l
- --line-numbers
- For 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-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.
- -r
- --reverse-sort
- Reverse the order of the sort (whether numeric or
alphabetic); let the last come first.
- -S
- --print-size
- 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 symbol sizes, unless --size-sort is also used in
which case a calculated size is displayed.
- -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.
- -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.
- -u
- --undefined-only
- Display only undefined symbols (those external to each
object file).
- -V
- --version
- Show the version number of nm and exit.
- -X
- This 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-only
- Display only defined symbols for each object file.
- --plugin name
- Load 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-sort
- Sort 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-syms
- Display 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.
- --synthetic
- Include 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.
- --target=bfdname
- Specify an object code format other than your system's
default format.
- @file
- Read command-line options from file. The options
read are inserted in place of the original @ file option. If
file does not exist, or cannot be read, then the option will be
treated literally, and not removed.
Options in file are separated by whitespace. A whitespace character
may be included in an option by surrounding the entire option in either
single or double quotes. Any character (including a backslash) may be
included by prefixing the character to be included with a backslash. The
file may itself contain additional @ file options; any such
options will be processed recursively.
SEE ALSO
ar(1),
objdump(1),
ranlib(1), and the Info entries for
binutils.
COPYRIGHT
Copyright (c) 1991-2016 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document under the
terms of the GNU Free Documentation License, Version 1.3 or any later version
published by the Free Software Foundation; with no Invariant Sections, with no
Front-Cover Texts, and with no Back-Cover Texts. A copy of the license is
included in the section entitled "GNU Free Documentation
License".