1NM(1) GNU Development Tools NM(1)
2
6 nm - list symbols from object files
7
9 nm [-A|-o|--print-file-name]
10 [-a|--debug-syms]
11 [-B|--format=bsd]
12 [-C|--demangle[=style]]
13 [-D|--dynamic]
14 [-fformat|--format=format]
15 [-g|--extern-only]
16 [-h|--help]
17 [--ifunc-chars=CHARS]
18 [-j|--format=just-symbols]
19 [-l|--line-numbers] [--inlines]
20 [-n|-v|--numeric-sort]
21 [-P|--portability]
22 [-p|--no-sort]
23 [-r|--reverse-sort]
24 [-S|--print-size]
25 [-s|--print-armap]
26 [-t radix|--radix=radix]
27 [-u|--undefined-only]
28 [-U|--defined-only]
29 [-V|--version]
30 [-W|--no-weak]
31 [-X 32_64]
32 [--no-demangle]
33 [--no-recurse-limit|--recurse-limit]]
34 [--plugin name]
35 [--size-sort]
36 [--special-syms]
37 [--synthetic]
38 [--target=bfdname]
39 [--unicode=method]
40 [--with-symbol-versions]
41 [--without-symbol-versions]
42 [objfile...]
43
45 GNU nm lists the symbols from object files objfile.... If no object
46 files are listed as arguments, nm assumes the file a.out.
47 For each symbol, nm shows:
49 • The symbol value, in the radix selected by options (see below), or
51 hexadecimal by default.
52 • The symbol type. At least the following types are used; others
54 are, as well, depending on the object file format. If lowercase,
55 the symbol is usually local; if uppercase, the symbol is global
56 (external). There are however a few lowercase symbols that are
57 shown for special global symbols ("u", "v" and "w").
58 "A" The symbol's value is absolute, and will not be changed by
60 further linking.
61 "B"
63 "b" The symbol is in the BSS data section. This section typically
64 contains zero-initialized or uninitialized data, although the
65 exact behavior is system dependent.
66 "C"
68 "c" The symbol is common. Common symbols are uninitialized data.
69 When linking, multiple common symbols may appear with the same
70 name. If the symbol is defined anywhere, the common symbols
71 are treated as undefined references. The lower case c
72 character is used when the symbol is in a special section for
73 small commons.
74 "D"
76 "d" The symbol is in the initialized data section.
77 "G"
79 "g" The symbol is in an initialized data section for small objects.
80 Some object file formats permit more efficient access to small
81 data objects, such as a global int variable as opposed to a
82 large global array.
83 "i" For PE format files this indicates that the symbol is in a
85 section specific to the implementation of DLLs.
86 For ELF format files this indicates that the symbol is an
88 indirect function. This is a GNU extension to the standard set
89 of ELF symbol types. It indicates a symbol which if referenced
90 by a relocation does not evaluate to its address, but instead
91 must be invoked at runtime. The runtime execution will then
92 return the value to be used in the relocation.
93 Note - the actual symbols display for GNU indirect symbols is
95 controlled by the --ifunc-chars command line option. If this
96 option has been provided then the first character in the string
97 will be used for global indirect function symbols. If the
98 string contains a second character then that will be used for
99 local indirect function symbols.
100 "I" The symbol is an indirect reference to another symbol.
102 "N" The symbol is a debugging symbol.
104 "n" The symbol is in the read-only data section.
106 "p" The symbol is in a stack unwind section.
108 "R"
110 "r" The symbol is in a read only data section.
111 "S"
113 "s" The symbol is in an uninitialized or zero-initialized data
114 section for small objects.
115 "T"
117 "t" The symbol is in the text (code) section.
118 "U" The symbol is undefined.
120 "u" The symbol is a unique global symbol. This is a GNU extension
122 to the standard set of ELF symbol bindings. For such a symbol
123 the dynamic linker will make sure that in the entire process
124 there is just one symbol with this name and type in use.
125 "V"
127 "v" The symbol is a weak object. When a weak defined symbol is
128 linked with a normal defined symbol, the normal defined symbol
129 is used with no error. When a weak undefined symbol is linked
130 and the symbol is not defined, the value of the weak symbol
131 becomes zero with no error. On some systems, uppercase
132 indicates that a default value has been specified.
133 "W"
135 "w" The symbol is a weak symbol that has not been specifically
136 tagged as a weak object symbol. When a weak defined symbol is
137 linked with a normal defined symbol, the normal defined symbol
138 is used with no error. When a weak undefined symbol is linked
139 and the symbol is not defined, the value of the symbol is
140 determined in a system-specific manner without error. On some
141 systems, uppercase indicates that a default value has been
142 specified.
143 "-" The symbol is a stabs symbol in an a.out object file. In this
145 case, the next values printed are the stabs other field, the
146 stabs desc field, and the stab type. Stabs symbols are used to
147 hold debugging information.
148 "?" The symbol type is unknown, or object file format specific.
150 • The symbol name. If a symbol has version information associated
152 with it, then the version information is displayed as well. If the
153 versioned symbol is undefined or hidden from linker, the version
154 string is displayed as a suffix to the symbol name, preceded by an
155 @ character. For example foo@VER_1. If the version is the default
156 version to be used when resolving unversioned references to the
157 symbol, then it is displayed as a suffix preceded by two @
158 characters. For example foo@@VER_2.
159
161 The long and short forms of options, shown here as alternatives, are
162 equivalent.
163 -A
165 -o
166 --print-file-name
167 Precede each symbol by the name of the input file (or archive
168 member) in which it was found, rather than identifying the input
169 file once only, before all of its symbols.
170 -a
172 --debug-syms
173 Display all symbols, even debugger-only symbols; normally these are
174 not listed.
175 -B The same as --format=bsd (for compatibility with the MIPS nm).
177 -C
179 --demangle[=style]
180 Decode (demangle) low-level symbol names into user-level names.
181 Besides removing any initial underscore prepended by the system,
182 this makes C++ function names readable. Different compilers have
183 different mangling styles. The optional demangling style argument
184 can be used to choose an appropriate demangling style for your
185 compiler.
186 --no-demangle
188 Do not demangle low-level symbol names. This is the default.
189 --recurse-limit
191 --no-recurse-limit
192 --recursion-limit
193 --no-recursion-limit
194 Enables or disables a limit on the amount of recursion performed
195 whilst demangling strings. Since the name mangling formats allow
196 for an infinite level of recursion it is possible to create strings
197 whose decoding will exhaust the amount of stack space available on
198 the host machine, triggering a memory fault. The limit tries to
199 prevent this from happening by restricting recursion to 2048 levels
200 of nesting.
201 The default is for this limit to be enabled, but disabling it may
203 be necessary in order to demangle truly complicated names. Note
204 however that if the recursion limit is disabled then stack
205 exhaustion is possible and any bug reports about such an event will
206 be rejected.
207 -D
209 --dynamic
210 Display the dynamic symbols rather than the normal symbols. This
211 is only meaningful for dynamic objects, such as certain types of
212 shared libraries.
213 -f format
215 --format=format
216 Use the output format format, which can be "bsd", "sysv", "posix"
217 or "just-symbols". The default is "bsd". Only the first character
218 of format is significant; it can be either upper or lower case.
219 -g
221 --extern-only
222 Display only external symbols.
223 -h
225 --help
226 Show a summary of the options to nm and exit.
227 --ifunc-chars=CHARS
229 When display GNU indirect function symbols nm will default to using
230 the "i" character for both local indirect functions and global
231 indirect functions. The --ifunc-chars option allows the user to
232 specify a string containing one or two characters. The first
233 character will be used for global indirect function symbols and the
234 second character, if present, will be used for local indirect
235 function symbols.
236 j The same as --format=just-symbols.
238 -l
240 --line-numbers
241 For each symbol, use debugging information to try to find a
242 filename and line number. For a defined symbol, look for the line
243 number of the address of the symbol. For an undefined symbol, look
244 for the line number of a relocation entry which refers to the
245 symbol. If line number information can be found, print it after
246 the other symbol information.
247 --inlines
249 When option -l is active, if the address belongs to a function that
250 was inlined, then this option causes the source information for all
251 enclosing scopes back to the first non-inlined function to be
252 printed as well. For example, if "main" inlines "callee1" which
253 inlines "callee2", and address is from "callee2", the source
254 information for "callee1" and "main" will also be printed.
255 -n
257 -v
258 --numeric-sort
259 Sort symbols numerically by their addresses, rather than
260 alphabetically by their names.
261 -p
263 --no-sort
264 Do not bother to sort the symbols in any order; print them in the
265 order encountered.
266 -P
268 --portability
269 Use the POSIX.2 standard output format instead of the default
270 format. Equivalent to -f posix.
271 -r
273 --reverse-sort
274 Reverse the order of the sort (whether numeric or alphabetic); let
275 the last come first.
276 -S
278 --print-size
279 Print both value and size of defined symbols for the "bsd" output
280 style. This option has no effect for object formats that do not
281 record symbol sizes, unless --size-sort is also used in which case
282 a calculated size is displayed.
283 -s
285 --print-armap
286 When listing symbols from archive members, include the index: a
287 mapping (stored in the archive by ar or ranlib) of which modules
288 contain definitions for which names.
289 -t radix
291 --radix=radix
292 Use radix as the radix for printing the symbol values. It must be
293 d for decimal, o for octal, or x for hexadecimal.
294 -u
296 --undefined-only
297 Display only undefined symbols (those external to each object
298 file). By default both defined and undefined symbols are
299 displayed.
300 -U
302 --defined-only
303 Display only defined symbols for each object file. By default both
304 defined and undefined symbols are displayed.
305 -V
307 --version
308 Show the version number of nm and exit.
309 -X This option is ignored for compatibility with the AIX version of
311 nm. It takes one parameter which must be the string 32_64. The
312 default mode of AIX nm corresponds to -X 32, which is not supported
313 by GNU nm.
314 --plugin name
316 Load the plugin called name to add support for extra target types.
317 This option is only available if the toolchain has been built with
318 plugin support enabled.
319 If --plugin is not provided, but plugin support has been enabled
321 then nm iterates over the files in ${libdir}/bfd-plugins in
322 alphabetic order and the first plugin that claims the object in
323 question is used.
324 Please note that this plugin search directory is not the one used
326 by ld's -plugin option. In order to make nm use the linker plugin
327 it must be copied into the ${libdir}/bfd-plugins directory. For
328 GCC based compilations the linker plugin is called
329 liblto_plugin.so.0.0.0. For Clang based compilations it is called
330 LLVMgold.so. The GCC plugin is always backwards compatible with
331 earlier versions, so it is sufficient to just copy the newest one.
332 --size-sort
334 Sort symbols by size. For ELF objects symbol sizes are read from
335 the ELF, for other object types the symbol sizes are computed as
336 the difference between the value of the symbol and the value of the
337 symbol with the next higher value. If the "bsd" output format is
338 used the size of the symbol is printed, rather than the value, and
339 -S must be used in order both size and value to be printed.
340 Note - this option does not work if --undefined-only has been
342 enabled as undefined symbols have no size.
343 --special-syms
345 Display symbols which have a target-specific special meaning.
346 These symbols are usually used by the target for some special
347 processing and are not normally helpful when included in the normal
348 symbol lists. For example for ARM targets this option would skip
349 the mapping symbols used to mark transitions between ARM code,
350 THUMB code and data.
351 --synthetic
353 Include synthetic symbols in the output. These are special symbols
354 created by the linker for various purposes. They are not shown by
355 default since they are not part of the binary's original source
356 code.
357 --unicode=[default|invalid|locale|escape|hex|highlight]
359 Controls the display of UTF-8 encoded multibyte characters in
360 strings. The default (--unicode=default) is to give them no
361 special treatment. The --unicode=locale option displays the
362 sequence in the current locale, which may or may not support them.
363 The options --unicode=hex and --unicode=invalid display them as hex
364 byte sequences enclosed by either angle brackets or curly braces.
365 The --unicode=escape option displays them as escape sequences
367 (\uxxxx) and the --unicode=highlight option displays them as escape
368 sequences highlighted in red (if supported by the output device).
369 The colouring is intended to draw attention to the presence of
370 unicode sequences where they might not be expected.
371 -W
373 --no-weak
374 Do not display weak symbols.
375 --with-symbol-versions
377 --without-symbol-versions
378 Enables or disables the display of symbol version information. The
379 version string is displayed as a suffix to the symbol name,
380 preceded by an @ character. For example foo@VER_1. If the version
381 is the default version to be used when resolving unversioned
382 references to the symbol then it is displayed as a suffix preceded
383 by two @ characters. For example foo@@VER_2. By default, symbol
384 version information is displayed.
385 --target=bfdname
387 Specify an object code format other than your system's default
388 format.
389 @file
391 Read command-line options from file. The options read are inserted
392 in place of the original @file option. If file does not exist, or
393 cannot be read, then the option will be treated literally, and not
394 removed.
395 Options in file are separated by whitespace. A whitespace
397 character may be included in an option by surrounding the entire
398 option in either single or double quotes. Any character (including
399 a backslash) may be included by prefixing the character to be
400 included with a backslash. The file may itself contain additional
401 @file options; any such options will be processed recursively.
402
404 ar(1), objdump(1), ranlib(1), and the Info entries for binutils.
405
407 Copyright (c) 1991-2023 Free Software Foundation, Inc.
408 Permission is granted to copy, distribute and/or modify this document
410 under the terms of the GNU Free Documentation License, Version 1.3 or
411 any later version published by the Free Software Foundation; with no
412 Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
413 Texts. A copy of the license is included in the section entitled "GNU
414 Free Documentation License".
415binutils-2.40.00 2023-07-30 NM(1)