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 a non-data, non-code, non-debug read-only
106 section.
107 "p" The symbol is in a stack unwind section.
109 "R"
111 "r" The symbol is in a read only data section.
112 "S"
114 "s" The symbol is in an uninitialized or zero-initialized data
115 section for small objects.
116 "T"
118 "t" The symbol is in the text (code) section.
119 "U" The symbol is undefined.
121 "u" The symbol is a unique global symbol. This is a GNU extension
123 to the standard set of ELF symbol bindings. For such a symbol
124 the dynamic linker will make sure that in the entire process
125 there is just one symbol with this name and type in use.
126 "V"
128 "v" The symbol is a weak object. When a weak defined symbol is
129 linked with a normal defined symbol, the normal defined symbol
130 is used with no error. When a weak undefined symbol is linked
131 and the symbol is not defined, the value of the weak symbol
132 becomes zero with no error. On some systems, uppercase
133 indicates that a default value has been specified.
134 "W"
136 "w" The symbol is a weak symbol that has not been specifically
137 tagged as a weak object symbol. When a weak defined symbol is
138 linked with a normal defined symbol, the normal defined symbol
139 is used with no error. When a weak undefined symbol is linked
140 and the symbol is not defined, the value of the symbol is
141 determined in a system-specific manner without error. On some
142 systems, uppercase indicates that a default value has been
143 specified.
144 "-" The symbol is a stabs symbol in an a.out object file. In this
146 case, the next values printed are the stabs other field, the
147 stabs desc field, and the stab type. Stabs symbols are used to
148 hold debugging information.
149 "?" The symbol type is unknown, or object file format specific.
151 • The symbol name. If a symbol has version information associated
153 with it, then the version information is displayed as well. If the
154 versioned symbol is undefined or hidden from linker, the version
155 string is displayed as a suffix to the symbol name, preceded by an
156 @ character. For example foo@VER_1. If the version is the default
157 version to be used when resolving unversioned references to the
158 symbol, then it is displayed as a suffix preceded by two @
159 characters. For example foo@@VER_2.
160
162 The long and short forms of options, shown here as alternatives, are
163 equivalent.
164 -A
166 -o
167 --print-file-name
168 Precede each symbol by the name of the input file (or archive
169 member) in which it was found, rather than identifying the input
170 file once only, before all of its symbols.
171 -a
173 --debug-syms
174 Display all symbols, even debugger-only symbols; normally these are
175 not listed.
176 -B The same as --format=bsd (for compatibility with the MIPS nm).
178 -C
180 --demangle[=style]
181 Decode (demangle) low-level symbol names into user-level names.
182 Besides removing any initial underscore prepended by the system,
183 this makes C++ function names readable. Different compilers have
184 different mangling styles. The optional demangling style argument
185 can be used to choose an appropriate demangling style for your
186 compiler.
187 --no-demangle
189 Do not demangle low-level symbol names. This is the default.
190 --recurse-limit
192 --no-recurse-limit
193 --recursion-limit
194 --no-recursion-limit
195 Enables or disables a limit on the amount of recursion performed
196 whilst demangling strings. Since the name mangling formats allow
197 for an infinite level of recursion it is possible to create strings
198 whose decoding will exhaust the amount of stack space available on
199 the host machine, triggering a memory fault. The limit tries to
200 prevent this from happening by restricting recursion to 2048 levels
201 of nesting.
202 The default is for this limit to be enabled, but disabling it may
204 be necessary in order to demangle truly complicated names. Note
205 however that if the recursion limit is disabled then stack
206 exhaustion is possible and any bug reports about such an event will
207 be rejected.
208 -D
210 --dynamic
211 Display the dynamic symbols rather than the normal symbols. This
212 is only meaningful for dynamic objects, such as certain types of
213 shared libraries.
214 -f format
216 --format=format
217 Use the output format format, which can be "bsd", "sysv", "posix"
218 or "just-symbols". The default is "bsd". Only the first character
219 of format is significant; it can be either upper or lower case.
220 -g
222 --extern-only
223 Display only external symbols.
224 -h
226 --help
227 Show a summary of the options to nm and exit.
228 --ifunc-chars=CHARS
230 When display GNU indirect function symbols nm will default to using
231 the "i" character for both local indirect functions and global
232 indirect functions. The --ifunc-chars option allows the user to
233 specify a string containing one or two characters. The first
234 character will be used for global indirect function symbols and the
235 second character, if present, will be used for local indirect
236 function symbols.
237 j The same as --format=just-symbols.
239 -l
241 --line-numbers
242 For each symbol, use debugging information to try to find a
243 filename and line number. For a defined symbol, look for the line
244 number of the address of the symbol. For an undefined symbol, look
245 for the line number of a relocation entry which refers to the
246 symbol. If line number information can be found, print it after
247 the other symbol information.
248 --inlines
250 When option -l is active, if the address belongs to a function that
251 was inlined, then this option causes the source information for all
252 enclosing scopes back to the first non-inlined function to be
253 printed as well. For example, if "main" inlines "callee1" which
254 inlines "callee2", and address is from "callee2", the source
255 information for "callee1" and "main" will also be printed.
256 -n
258 -v
259 --numeric-sort
260 Sort symbols numerically by their addresses, rather than
261 alphabetically by their names.
262 -p
264 --no-sort
265 Do not bother to sort the symbols in any order; print them in the
266 order encountered.
267 -P
269 --portability
270 Use the POSIX.2 standard output format instead of the default
271 format. Equivalent to -f posix.
272 -r
274 --reverse-sort
275 Reverse the order of the sort (whether numeric or alphabetic); let
276 the last come first.
277 -S
279 --print-size
280 Print both value and size of defined symbols for the "bsd" output
281 style. This option has no effect for object formats that do not
282 record symbol sizes, unless --size-sort is also used in which case
283 a calculated size is displayed.
284 -s
286 --print-armap
287 When listing symbols from archive members, include the index: a
288 mapping (stored in the archive by ar or ranlib) of which modules
289 contain definitions for which names.
290 -t radix
292 --radix=radix
293 Use radix as the radix for printing the symbol values. It must be
294 d for decimal, o for octal, or x for hexadecimal.
295 -u
297 --undefined-only
298 Display only undefined symbols (those external to each object
299 file). By default both defined and undefined symbols are
300 displayed.
301 -U
303 --defined-only
304 Display only defined symbols for each object file. By default both
305 defined and undefined symbols are displayed.
306 -V
308 --version
309 Show the version number of nm and exit.
310 -X This option is ignored for compatibility with the AIX version of
312 nm. It takes one parameter which must be the string 32_64. The
313 default mode of AIX nm corresponds to -X 32, which is not supported
314 by GNU nm.
315 --plugin name
317 Load the plugin called name to add support for extra target types.
318 This option is only available if the toolchain has been built with
319 plugin support enabled.
320 If --plugin is not provided, but plugin support has been enabled
322 then nm iterates over the files in ${libdir}/bfd-plugins in
323 alphabetic order and the first plugin that claims the object in
324 question is used.
325 Please note that this plugin search directory is not the one used
327 by ld's -plugin option. In order to make nm use the linker plugin
328 it must be copied into the ${libdir}/bfd-plugins directory. For
329 GCC based compilations the linker plugin is called
330 liblto_plugin.so.0.0.0. For Clang based compilations it is called
331 LLVMgold.so. The GCC plugin is always backwards compatible with
332 earlier versions, so it is sufficient to just copy the newest one.
333 --size-sort
335 Sort symbols by size. For ELF objects symbol sizes are read from
336 the ELF, for other object types the symbol sizes are computed as
337 the difference between the value of the symbol and the value of the
338 symbol with the next higher value. If the "bsd" output format is
339 used the size of the symbol is printed, rather than the value, and
340 -S must be used in order both size and value to be printed.
341 Note - this option does not work if --undefined-only has been
343 enabled as undefined symbols have no size.
344 --special-syms
346 Display symbols which have a target-specific special meaning.
347 These symbols are usually used by the target for some special
348 processing and are not normally helpful when included in the normal
349 symbol lists. For example for ARM targets this option would skip
350 the mapping symbols used to mark transitions between ARM code,
351 THUMB code and data.
352 --synthetic
354 Include synthetic symbols in the output. These are special symbols
355 created by the linker for various purposes. They are not shown by
356 default since they are not part of the binary's original source
357 code.
358 --unicode=[default|invalid|locale|escape|hex|highlight]
360 Controls the display of UTF-8 encoded multibyte characters in
361 strings. The default (--unicode=default) is to give them no
362 special treatment. The --unicode=locale option displays the
363 sequence in the current locale, which may or may not support them.
364 The options --unicode=hex and --unicode=invalid display them as hex
365 byte sequences enclosed by either angle brackets or curly braces.
366 The --unicode=escape option displays them as escape sequences
368 (\uxxxx) and the --unicode=highlight option displays them as escape
369 sequences highlighted in red (if supported by the output device).
370 The colouring is intended to draw attention to the presence of
371 unicode sequences where they might not be expected.
372 -W
374 --no-weak
375 Do not display weak symbols.
376 --with-symbol-versions
378 --without-symbol-versions
379 Enables or disables the display of symbol version information. The
380 version string is displayed as a suffix to the symbol name,
381 preceded by an @ character. For example foo@VER_1. If the version
382 is the default version to be used when resolving unversioned
383 references to the symbol then it is displayed as a suffix preceded
384 by two @ characters. For example foo@@VER_2. By default, symbol
385 version information is displayed.
386 --target=bfdname
388 Specify an object code format other than your system's default
389 format.
390 @file
392 Read command-line options from file. The options read are inserted
393 in place of the original @file option. If file does not exist, or
394 cannot be read, then the option will be treated literally, and not
395 removed.
396 Options in file are separated by whitespace. A whitespace
398 character may be included in an option by surrounding the entire
399 option in either single or double quotes. Any character (including
400 a backslash) may be included by prefixing the character to be
401 included with a backslash. The file may itself contain additional
402 @file options; any such options will be processed recursively.
403
405 ar(1), objdump(1), ranlib(1), and the Info entries for binutils.
406
408 Copyright (c) 1991-2023 Free Software Foundation, Inc.
409 Permission is granted to copy, distribute and/or modify this document
411 under the terms of the GNU Free Documentation License, Version 1.3 or
412 any later version published by the Free Software Foundation; with no
413 Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
414 Texts. A copy of the license is included in the section entitled "GNU
415 Free Documentation License".
416binutils-2.41 2023-08-16 NM(1)