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]
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 method] [--unicode=method]
29          [-V|--version]
30          [-X 32_64]
31          [--defined-only]
32          [--no-demangle]
33          [--no-recurse-limit|--recurse-limit]]
34          [--plugin name]
35          [--size-sort]
36          [--special-syms]
37          [--synthetic]
38          [--target=bfdname]
39          [--with-symbol-versions]
40          [--without-symbol-versions]
41          [objfile...]
42

DESCRIPTION

44       GNU nm lists the symbols from object files objfile....  If no object
45       files are listed as arguments, nm assumes the file a.out.
46
47       For each symbol, nm shows:
48
49       •   The symbol value, in the radix selected by options (see below), or
50           hexadecimal by default.
51
52       •   The symbol type.  At least the following types are used; others
53           are, as well, depending on the object file format.  If lowercase,
54           the symbol is usually local; if uppercase, the symbol is global
55           (external).  There are however a few lowercase symbols that are
56           shown for special global symbols ("u", "v" and "w").
57
58           "A" The symbol's value is absolute, and will not be changed by
59               further linking.
60
61           "B"
62           "b" The symbol is in the BSS data section.  This section typically
63               contains zero-initialized or uninitialized data, although the
64               exact behavior is system dependent.
65
66           "C"
67           "c" The symbol is common.  Common symbols are uninitialized data.
68               When linking, multiple common symbols may appear with the same
69               name.  If the symbol is defined anywhere, the common symbols
70               are treated as undefined references.  The lower case c
71               character is used when the symbol is in a special section for
72               small commons.
73
74           "D"
75           "d" The symbol is in the initialized data section.
76
77           "G"
78           "g" The symbol is in an initialized data section for small objects.
79               Some object file formats permit more efficient access to small
80               data objects, such as a global int variable as opposed to a
81               large global array.
82
83           "i" For PE format files this indicates that the symbol is in a
84               section specific to the implementation of DLLs.
85
86               For ELF format files this indicates that the symbol is an
87               indirect function.  This is a GNU extension to the standard set
88               of ELF symbol types.  It indicates a symbol which if referenced
89               by a relocation does not evaluate to its address, but instead
90               must be invoked at runtime.  The runtime execution will then
91               return the value to be used in the relocation.
92
93               Note - the actual symbols display for GNU indirect symbols is
94               controlled by the --ifunc-chars command line option.  If this
95               option has been provided then the first character in the string
96               will be used for global indirect function symbols.  If the
97               string contains a second character then that will be used for
98               local indirect function symbols.
99
100           "I" The symbol is an indirect reference to another symbol.
101
102           "N" The symbol is a debugging symbol.
103
104           "n" The symbol is in the read-only data section.
105
106           "p" The symbol is in a stack unwind section.
107
108           "R"
109           "r" The symbol is in a read only data section.
110
111           "S"
112           "s" The symbol is in an uninitialized or zero-initialized data
113               section for small objects.
114
115           "T"
116           "t" The symbol is in the text (code) section.
117
118           "U" The symbol is undefined.
119
120           "u" The symbol is a unique global symbol.  This is a GNU extension
121               to the standard set of ELF symbol bindings.  For such a symbol
122               the dynamic linker will make sure that in the entire process
123               there is just one symbol with this name and type in use.
124
125           "V"
126           "v" The symbol is a weak object.  When a weak defined symbol is
127               linked with a normal defined symbol, the normal defined symbol
128               is used with no error.  When a weak undefined symbol is linked
129               and the symbol is not defined, the value of the weak symbol
130               becomes zero with no error.  On some systems, uppercase
131               indicates that a default value has been specified.
132
133           "W"
134           "w" The symbol is a weak symbol that has not been specifically
135               tagged as a weak object symbol.  When a weak defined symbol is
136               linked with a normal defined symbol, the normal defined symbol
137               is used with no error.  When a weak undefined symbol is linked
138               and the symbol is not defined, the value of the symbol is
139               determined in a system-specific manner without error.  On some
140               systems, uppercase indicates that a default value has been
141               specified.
142
143           "-" The symbol is a stabs symbol in an a.out object file.  In this
144               case, the next values printed are the stabs other field, the
145               stabs desc field, and the stab type.  Stabs symbols are used to
146               hold debugging information.
147
148           "?" The symbol type is unknown, or object file format specific.
149
150       •   The symbol name.  If a symbol has version information associated
151           with it, then the version information is displayed as well.  If the
152           versioned symbol is undefined or hidden from linker, the version
153           string is displayed as a suffix to the symbol name, preceded by an
154           @ character.  For example foo@VER_1.  If the version is the default
155           version to be used when resolving unversioned references to the
156           symbol, then it is displayed as a suffix preceded by two @
157           characters.  For example foo@@VER_2.
158

OPTIONS

160       The long and short forms of options, shown here as alternatives, are
161       equivalent.
162
163       -A
164       -o
165       --print-file-name
166           Precede each symbol by the name of the input file (or archive
167           member) in which it was found, rather than identifying the input
168           file once only, before all of its symbols.
169
170       -a
171       --debug-syms
172           Display all symbols, even debugger-only symbols; normally these are
173           not listed.
174
175       -B  The same as --format=bsd (for compatibility with the MIPS nm).
176
177       -C
178       --demangle[=style]
179           Decode (demangle) low-level symbol names into user-level names.
180           Besides removing any initial underscore prepended by the system,
181           this makes C++ function names readable. Different compilers have
182           different mangling styles. The optional demangling style argument
183           can be used to choose an appropriate demangling style for your
184           compiler.
185
186       --no-demangle
187           Do not demangle low-level symbol names.  This is the default.
188
189       --recurse-limit
190       --no-recurse-limit
191       --recursion-limit
192       --no-recursion-limit
193           Enables or disables a limit on the amount of recursion performed
194           whilst demangling strings.  Since the name mangling formats allow
195           for an infinite level of recursion it is possible to create strings
196           whose decoding will exhaust the amount of stack space available on
197           the host machine, triggering a memory fault.  The limit tries to
198           prevent this from happening by restricting recursion to 2048 levels
199           of nesting.
200
201           The default is for this limit to be enabled, but disabling it may
202           be necessary in order to demangle truly complicated names.  Note
203           however that if the recursion limit is disabled then stack
204           exhaustion is possible and any bug reports about such an event will
205           be rejected.
206
207       -D
208       --dynamic
209           Display the dynamic symbols rather than the normal symbols.  This
210           is only meaningful for dynamic objects, such as certain types of
211           shared libraries.
212
213       -f format
214       --format=format
215           Use the output format format, which can be "bsd", "sysv", "posix"
216           or "just-symbols".  The default is "bsd".  Only the first character
217           of format is significant; it can be either upper or lower case.
218
219       -g
220       --extern-only
221           Display only external symbols.
222
223       -h
224       --help
225           Show a summary of the options to nm and exit.
226
227       --ifunc-chars=CHARS
228           When display GNU indirect function symbols nm will default to using
229           the "i" character for both local indirect functions and global
230           indirect functions.  The --ifunc-chars option allows the user to
231           specify a string containing one or two characters. The first
232           character will be used for global indirect function symbols and the
233           second character, if present, will be used for local indirect
234           function symbols.
235
236       j   The same as --format=just-symbols.
237
238       -l
239       --line-numbers
240           For each symbol, use debugging information to try to find a
241           filename and line number.  For a defined symbol, look for the line
242           number of the address of the symbol.  For an undefined symbol, look
243           for the line number of a relocation entry which refers to the
244           symbol.  If line number information can be found, print it after
245           the other symbol information.
246
247       --inlines
248           When option -l is active, if the address belongs to a function that
249           was inlined, then this option causes the source information for all
250           enclosing scopes back to the first non-inlined function to be
251           printed as well.  For example, if "main" inlines "callee1" which
252           inlines "callee2", and address is from "callee2", the source
253           information for "callee1" and "main" will also be printed.
254
255       -n
256       -v
257       --numeric-sort
258           Sort symbols numerically by their addresses, rather than
259           alphabetically by their names.
260
261       -p
262       --no-sort
263           Do not bother to sort the symbols in any order; print them in the
264           order encountered.
265
266       -P
267       --portability
268           Use the POSIX.2 standard output format instead of the default
269           format.  Equivalent to -f posix.
270
271       -r
272       --reverse-sort
273           Reverse the order of the sort (whether numeric or alphabetic); let
274           the last come first.
275
276       -S
277       --print-size
278           Print both value and size of defined symbols for the "bsd" output
279           style.  This option has no effect for object formats that do not
280           record symbol sizes, unless --size-sort is also used in which case
281           a calculated size is displayed.
282
283       -s
284       --print-armap
285           When listing symbols from archive members, include the index: a
286           mapping (stored in the archive by ar or ranlib) of which modules
287           contain definitions for which names.
288
289       -t radix
290       --radix=radix
291           Use radix as the radix for printing the symbol values.  It must be
292           d for decimal, o for octal, or x for hexadecimal.
293
294       -u
295       --undefined-only
296           Display only undefined symbols (those external to each object
297           file).
298
299       -U [d|i|l|e|x|h]
300       --unicode=[default|invalid|locale|escape|hex|highlight]
301           Controls the display of UTF-8 encoded multibyte characters in
302           strings.  The default (--unicode=default) is to give them no
303           special treatment.  The --unicode=locale option displays the
304           sequence in the current locale, which may or may not support them.
305           The options --unicode=hex and --unicode=invalid display them as hex
306           byte sequences enclosed by either angle brackets or curly braces.
307
308           The --unicode=escape option displays them as escape sequences
309           (\uxxxx) and the --unicode=highlight option displays them as escape
310           sequences highlighted in red (if supported by the output device).
311           The colouring is intended to draw attention to the presence of
312           unicode sequences where they might not be expected.
313
314       -V
315       --version
316           Show the version number of nm and exit.
317
318       -X  This option is ignored for compatibility with the AIX version of
319           nm.  It takes one parameter which must be the string 32_64.  The
320           default mode of AIX nm corresponds to -X 32, which is not supported
321           by GNU nm.
322
323       --defined-only
324           Display only defined symbols for each object file.
325
326       --plugin name
327           Load the plugin called name to add support for extra target types.
328           This option is only available if the toolchain has been built with
329           plugin support enabled.
330
331           If --plugin is not provided, but plugin support has been enabled
332           then nm iterates over the files in ${libdir}/bfd-plugins in
333           alphabetic order and the first plugin that claims the object in
334           question is used.
335
336           Please note that this plugin search directory is not the one used
337           by ld's -plugin option.  In order to make nm use the  linker plugin
338           it must be copied into the ${libdir}/bfd-plugins directory.  For
339           GCC based compilations the linker plugin is called
340           liblto_plugin.so.0.0.0.  For Clang based compilations it is called
341           LLVMgold.so.  The GCC plugin is always backwards compatible with
342           earlier versions, so it is sufficient to just copy the newest one.
343
344       --size-sort
345           Sort symbols by size.  For ELF objects symbol sizes are read from
346           the ELF, for other object types the symbol sizes are computed as
347           the difference between the value of the symbol and the value of the
348           symbol with the next higher value.  If the "bsd" output format is
349           used the size of the symbol is printed, rather than the value, and
350           -S must be used in order both size and value to be printed.
351
352       --special-syms
353           Display symbols which have a target-specific special meaning.
354           These symbols are usually used by the target for some special
355           processing and are not normally helpful when included in the normal
356           symbol lists.  For example for ARM targets this option would skip
357           the mapping symbols used to mark transitions between ARM code,
358           THUMB code and data.
359
360       --synthetic
361           Include synthetic symbols in the output.  These are special symbols
362           created by the linker for various purposes.  They are not shown by
363           default since they are not part of the binary's original source
364           code.
365
366       --with-symbol-versions
367       --without-symbol-versions
368           Enables or disables the display of symbol version information.  The
369           version string is displayed as a suffix to the symbol name,
370           preceded by an @ character.  For example foo@VER_1.  If the version
371           is the default version to be used when resolving unversioned
372           references to the symbol then it is displayed as a suffix preceded
373           by two @ characters.  For example foo@@VER_2.  By default, symbol
374           version information is displayed.
375
376       --target=bfdname
377           Specify an object code format other than your system's default
378           format.
379
380       @file
381           Read command-line options from file.  The options read are inserted
382           in place of the original @file option.  If file does not exist, or
383           cannot be read, then the option will be treated literally, and not
384           removed.
385
386           Options in file are separated by whitespace.  A whitespace
387           character may be included in an option by surrounding the entire
388           option in either single or double quotes.  Any character (including
389           a backslash) may be included by prefixing the character to be
390           included with a backslash.  The file may itself contain additional
391           @file options; any such options will be processed recursively.
392

SEE ALSO

394       ar(1), objdump(1), ranlib(1), and the Info entries for binutils.
395
397       Copyright (c) 1991-2022 Free Software Foundation, Inc.
398
399       Permission is granted to copy, distribute and/or modify this document
400       under the terms of the GNU Free Documentation License, Version 1.3 or
401       any later version published by the Free Software Foundation; with no
402       Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
403       Texts.  A copy of the license is included in the section entitled "GNU
404       Free Documentation License".
405
406
407
408binutils-2.38                     2022-07-20                             NM(1)
Impressum