1NM(1)                        GNU Development Tools                       NM(1)
2
3
4

NAME

6       nm - list symbols from object files
7

SYNOPSIS

9       nm [-A|-o|--print-file-name] [-a|--debug-syms]
10          [-B|--format=bsd] [-C|--demangle[=style]]
11          [-D|--dynamic] [-fformat|--format=format]
12          [-g|--extern-only] [-h|--help]
13          [-l|--line-numbers] [--inlines]
14          [-n|-v|--numeric-sort]
15          [-P|--portability] [-p|--no-sort]
16          [-r|--reverse-sort] [-S|--print-size]
17          [-s|--print-armap] [-t radix|--radix=radix]
18          [-u|--undefined-only] [-V|--version]
19          [-X 32_64] [--defined-only] [--no-demangle]
20          [--plugin name]
21          [--no-recurse-limit|--recurse-limit]]
22          [--size-sort] [--special-syms]
23          [--synthetic] [--with-symbol-versions] [--target=bfdname]
24          [objfile...]
25

DESCRIPTION

27       GNU nm lists the symbols from object files objfile....  If no object
28       files are listed as arguments, nm assumes the file a.out.
29
30       For each symbol, nm shows:
31
32       ·   The symbol value, in the radix selected by options (see below), or
33           hexadecimal by default.
34
35       ·   The symbol type.  At least the following types are used; others
36           are, as well, depending on the object file format.  If lowercase,
37           the symbol is usually local; if uppercase, the symbol is global
38           (external).  There are however a few lowercase symbols that are
39           shown for special global symbols ("u", "v" and "w").
40
41           "A" The symbol's value is absolute, and will not be changed by
42               further linking.
43
44           "B"
45           "b" The symbol is in the BSS data section.  This section typically
46               contains zero-initialized or uninitialized data, although the
47               exact behavior is system dependent.
48
49           "C" The symbol is common.  Common symbols are uninitialized data.
50               When linking, multiple common symbols may appear with the same
51               name.  If the symbol is defined anywhere, the common symbols
52               are treated as undefined references.
53
54           "D"
55           "d" The symbol is in the initialized data section.
56
57           "G"
58           "g" The symbol is in an initialized data section for small objects.
59               Some object file formats permit more efficient access to small
60               data objects, such as a global int variable as opposed to a
61               large global array.
62
63           "i" For PE format files this indicates that the symbol is in a
64               section specific to the implementation of DLLs.  For ELF format
65               files this indicates that the symbol is an indirect function.
66               This is a GNU extension to the standard set of ELF symbol
67               types.  It indicates a symbol which if referenced by a
68               relocation does not evaluate to its address, but instead must
69               be invoked at runtime.  The runtime execution will then return
70               the value to be used in the relocation.
71
72           "I" The symbol is an indirect reference to another symbol.
73
74           "N" The symbol is a debugging symbol.
75
76           "n" The symbol is in the read-only data section.
77
78           "p" The symbol is in a stack unwind section.
79
80           "R"
81           "r" The symbol is in a read only data section.
82
83           "S"
84           "s" The symbol is in an uninitialized or zero-initialized data
85               section for small objects.
86
87           "T"
88           "t" The symbol is in the text (code) section.
89
90           "U" The symbol is undefined.
91
92           "u" The symbol is a unique global symbol.  This is a GNU extension
93               to the standard set of ELF symbol bindings.  For such a symbol
94               the dynamic linker will make sure that in the entire process
95               there is just one symbol with this name and type in use.
96
97           "V"
98           "v" The symbol is a weak object.  When a weak defined symbol is
99               linked with a normal defined symbol, the normal defined symbol
100               is used with no error.  When a weak undefined symbol is linked
101               and the symbol is not defined, the value of the weak symbol
102               becomes zero with no error.  On some systems, uppercase
103               indicates that a default value has been specified.
104
105           "W"
106           "w" The symbol is a weak symbol that has not been specifically
107               tagged as a weak object symbol.  When a weak defined symbol is
108               linked with a normal defined symbol, the normal defined symbol
109               is used with no error.  When a weak undefined symbol is linked
110               and the symbol is not defined, the value of the symbol is
111               determined in a system-specific manner without error.  On some
112               systems, uppercase indicates that a default value has been
113               specified.
114
115           "-" The symbol is a stabs symbol in an a.out object file.  In this
116               case, the next values printed are the stabs other field, the
117               stabs desc field, and the stab type.  Stabs symbols are used to
118               hold debugging information.
119
120           "?" The symbol type is unknown, or object file format specific.
121
122       ·   The symbol name.
123

OPTIONS

125       The long and short forms of options, shown here as alternatives, are
126       equivalent.
127
128       -A
129       -o
130       --print-file-name
131           Precede each symbol by the name of the input file (or archive
132           member) in which it was found, rather than identifying the input
133           file once only, before all of its symbols.
134
135       -a
136       --debug-syms
137           Display all symbols, even debugger-only symbols; normally these are
138           not listed.
139
140       -B  The same as --format=bsd (for compatibility with the MIPS nm).
141
142       -C
143       --demangle[=style]
144           Decode (demangle) low-level symbol names into user-level names.
145           Besides removing any initial underscore prepended by the system,
146           this makes C++ function names readable. Different compilers have
147           different mangling styles. The optional demangling style argument
148           can be used to choose an appropriate demangling style for your
149           compiler.
150
151       --no-demangle
152           Do not demangle low-level symbol names.  This is the default.
153
154       --recurse-limit
155       --no-recurse-limit
156       --recursion-limit
157       --no-recursion-limit
158           Enables or disables a limit on the amount of recursion performed
159           whilst demangling strings.  Since the name mangling formats allow
160           for an inifinite level of recursion it is possible to create
161           strings whose decoding will exhaust the amount of stack space
162           available on the host machine, triggering a memory fault.  The
163           limit tries to prevent this from happening by restricting recursion
164           to 2048 levels of nesting.
165
166           The default is for this limit to be enabled, but disabling it may
167           be necessary in order to demangle truly complicated names.  Note
168           however that if the recursion limit is disabled then stack
169           exhaustion is possible and any bug reports about such an event will
170           be rejected.
171
172       -D
173       --dynamic
174           Display the dynamic symbols rather than the normal symbols.  This
175           is only meaningful for dynamic objects, such as certain types of
176           shared libraries.
177
178       -f format
179       --format=format
180           Use the output format format, which can be "bsd", "sysv", or
181           "posix".  The default is "bsd".  Only the first character of format
182           is significant; it can be either upper or lower case.
183
184       -g
185       --extern-only
186           Display only external symbols.
187
188       -h
189       --help
190           Show a summary of the options to nm and exit.
191
192       -l
193       --line-numbers
194           For each symbol, use debugging information to try to find a
195           filename and line number.  For a defined symbol, look for the line
196           number of the address of the symbol.  For an undefined symbol, look
197           for the line number of a relocation entry which refers to the
198           symbol.  If line number information can be found, print it after
199           the other symbol information.
200
201       --inlines
202           When option -l is active, if the address belongs to a function that
203           was inlined, then this option causes the source information for all
204           enclosing scopes back to the first non-inlined function to be
205           printed as well.  For example, if "main" inlines "callee1" which
206           inlines "callee2", and address is from "callee2", the source
207           information for "callee1" and "main" will also be printed.
208
209       -n
210       -v
211       --numeric-sort
212           Sort symbols numerically by their addresses, rather than
213           alphabetically by their names.
214
215       -p
216       --no-sort
217           Do not bother to sort the symbols in any order; print them in the
218           order encountered.
219
220       -P
221       --portability
222           Use the POSIX.2 standard output format instead of the default
223           format.  Equivalent to -f posix.
224
225       -r
226       --reverse-sort
227           Reverse the order of the sort (whether numeric or alphabetic); let
228           the last come first.
229
230       -S
231       --print-size
232           Print both value and size of defined symbols for the "bsd" output
233           style.  This option has no effect for object formats that do not
234           record symbol sizes, unless --size-sort is also used in which case
235           a calculated size is displayed.
236
237       -s
238       --print-armap
239           When listing symbols from archive members, include the index: a
240           mapping (stored in the archive by ar or ranlib) of which modules
241           contain definitions for which names.
242
243       -t radix
244       --radix=radix
245           Use radix as the radix for printing the symbol values.  It must be
246           d for decimal, o for octal, or x for hexadecimal.
247
248       -u
249       --undefined-only
250           Display only undefined symbols (those external to each object
251           file).
252
253       -V
254       --version
255           Show the version number of nm and exit.
256
257       -X  This option is ignored for compatibility with the AIX version of
258           nm.  It takes one parameter which must be the string 32_64.  The
259           default mode of AIX nm corresponds to -X 32, which is not supported
260           by GNU nm.
261
262       --defined-only
263           Display only defined symbols for each object file.
264
265       --plugin name
266           Load the plugin called name to add support for extra target types.
267           This option is only available if the toolchain has been built with
268           plugin support enabled.
269
270           If --plugin is not provided, but plugin support has been enabled
271           then nm iterates over the files in ${libdir}/bfd-plugins in
272           alphabetic order and the first plugin that claims the object in
273           question is used.
274
275           Please note that this plugin search directory is not the one used
276           by ld's -plugin option.  In order to make nm use the  linker plugin
277           it must be copied into the ${libdir}/bfd-plugins directory.  For
278           GCC based compilations the linker plugin is called
279           liblto_plugin.so.0.0.0.  For Clang based compilations it is called
280           LLVMgold.so.  The GCC plugin is always backwards compatible with
281           earlier versions, so it is sufficient to just copy the newest one.
282
283       --size-sort
284           Sort symbols by size.  For ELF objects symbol sizes are read from
285           the ELF, for other object types the symbol sizes are computed as
286           the difference between the value of the symbol and the value of the
287           symbol with the next higher value.  If the "bsd" output format is
288           used the size of the symbol is printed, rather than the value, and
289           -S must be used in order both size and value to be printed.
290
291       --special-syms
292           Display symbols which have a target-specific special meaning.
293           These symbols are usually used by the target for some special
294           processing and are not normally helpful when included in the normal
295           symbol lists.  For example for ARM targets this option would skip
296           the mapping symbols used to mark transitions between ARM code,
297           THUMB code and data.
298
299       --synthetic
300           Include synthetic symbols in the output.  These are special symbols
301           created by the linker for various purposes.  They are not shown by
302           default since they are not part of the binary's original source
303           code.
304
305       --with-symbol-versions
306           Enables the display of symbol version information if any exists.
307           The version string is displayed as a suffix to the symbol name,
308           preceeded by an @ character.  For example foo@VER_1.  If the
309           version is the default version to be used when resolving
310           unversioned references to the symbol then it is displayed as a
311           suffix preceeded by two @ characters.  For example foo@@VER_2.
312
313       --target=bfdname
314           Specify an object code format other than your system's default
315           format.
316
317       @file
318           Read command-line options from file.  The options read are inserted
319           in place of the original @file option.  If file does not exist, or
320           cannot be read, then the option will be treated literally, and not
321           removed.
322
323           Options in file are separated by whitespace.  A whitespace
324           character may be included in an option by surrounding the entire
325           option in either single or double quotes.  Any character (including
326           a backslash) may be included by prefixing the character to be
327           included with a backslash.  The file may itself contain additional
328           @file options; any such options will be processed recursively.
329

SEE ALSO

331       ar(1), objdump(1), ranlib(1), and the Info entries for binutils.
332
334       Copyright (c) 1991-2020 Free Software Foundation, Inc.
335
336       Permission is granted to copy, distribute and/or modify this document
337       under the terms of the GNU Free Documentation License, Version 1.3 or
338       any later version published by the Free Software Foundation; with no
339       Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
340       Texts.  A copy of the license is included in the section entitled "GNU
341       Free Documentation License".
342
343
344
345binutils-2.34                     2020-02-17                             NM(1)
Impressum