1NM(1) GNU Development Tools NM(1)
2
6 nm - list symbols from object files
7
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] [--size-sort] [--special-syms]
21 [--synthetic] [--with-symbol-versions] [--target=bfdname]
22 [objfile...]
23
25 GNU nm lists the symbols from object files objfile.... If no object
26 files are listed as arguments, nm assumes the file a.out.
27 For each symbol, nm shows:
29 · The symbol value, in the radix selected by options (see below), or
31 hexadecimal by default.
32 · The symbol type. At least the following types are used; others
34 are, as well, depending on the object file format. If lowercase,
35 the symbol is usually local; if uppercase, the symbol is global
36 (external). There are however a few lowercase symbols that are
37 shown for special global symbols ("u", "v" and "w").
38 "A" The symbol's value is absolute, and will not be changed by
40 further linking.
41 "B"
43 "b" The symbol is in the BSS data section. This section typically
44 contains zero-initialized or uninitialized data, although the
45 exact behavior is system dependent.
46 "C" The symbol is common. Common symbols are uninitialized data.
48 When linking, multiple common symbols may appear with the same
49 name. If the symbol is defined anywhere, the common symbols
50 are treated as undefined references.
51 "D"
53 "d" The symbol is in the initialized data section.
54 "G"
56 "g" The symbol is in an initialized data section for small objects.
57 Some object file formats permit more efficient access to small
58 data objects, such as a global int variable as opposed to a
59 large global array.
60 "i" For PE format files this indicates that the symbol is in a
62 section specific to the implementation of DLLs. For ELF format
63 files this indicates that the symbol is an indirect function.
64 This is a GNU extension to the standard set of ELF symbol
65 types. It indicates a symbol which if referenced by a
66 relocation does not evaluate to its address, but instead must
67 be invoked at runtime. The runtime execution will then return
68 the value to be used in the relocation.
69 "I" The symbol is an indirect reference to another symbol.
71 "N" The symbol is a debugging symbol.
73 "p" The symbols is in a stack unwind section.
75 "R"
77 "r" The symbol is in a read only data section.
78 "S"
80 "s" The symbol is in an uninitialized or zero-initialized data
81 section for small objects.
82 "T"
84 "t" The symbol is in the text (code) section.
85 "U" The symbol is undefined.
87 "u" The symbol is a unique global symbol. This is a GNU extension
89 to the standard set of ELF symbol bindings. For such a symbol
90 the dynamic linker will make sure that in the entire process
91 there is just one symbol with this name and type in use.
92 "V"
94 "v" The symbol is a weak object. When a weak defined symbol is
95 linked with a normal defined symbol, the normal defined symbol
96 is used with no error. When a weak undefined symbol is linked
97 and the symbol is not defined, the value of the weak symbol
98 becomes zero with no error. On some systems, uppercase
99 indicates that a default value has been specified.
100 "W"
102 "w" The symbol is a weak symbol that has not been specifically
103 tagged as a weak object symbol. When a weak defined symbol is
104 linked with a normal defined symbol, the normal defined symbol
105 is used with no error. When a weak undefined symbol is linked
106 and the symbol is not defined, the value of the symbol is
107 determined in a system-specific manner without error. On some
108 systems, uppercase indicates that a default value has been
109 specified.
110 "-" The symbol is a stabs symbol in an a.out object file. In this
112 case, the next values printed are the stabs other field, the
113 stabs desc field, and the stab type. Stabs symbols are used to
114 hold debugging information.
115 "?" The symbol type is unknown, or object file format specific.
117 · The symbol name.
119
121 The long and short forms of options, shown here as alternatives, are
122 equivalent.
123 -A
125 -o
126 --print-file-name
127 Precede each symbol by the name of the input file (or archive
128 member) in which it was found, rather than identifying the input
129 file once only, before all of its symbols.
130 -a
132 --debug-syms
133 Display all symbols, even debugger-only symbols; normally these are
134 not listed.
135 -B The same as --format=bsd (for compatibility with the MIPS nm).
137 -C
139 --demangle[=style]
140 Decode (demangle) low-level symbol names into user-level names.
141 Besides removing any initial underscore prepended by the system,
142 this makes C++ function names readable. Different compilers have
143 different mangling styles. The optional demangling style argument
144 can be used to choose an appropriate demangling style for your
145 compiler.
146 --no-demangle
148 Do not demangle low-level symbol names. This is the default.
149 -D
151 --dynamic
152 Display the dynamic symbols rather than the normal symbols. This
153 is only meaningful for dynamic objects, such as certain types of
154 shared libraries.
155 -f format
157 --format=format
158 Use the output format format, which can be "bsd", "sysv", or
159 "posix". The default is "bsd". Only the first character of format
160 is significant; it can be either upper or lower case.
161 -g
163 --extern-only
164 Display only external symbols.
165 -h
167 --help
168 Show a summary of the options to nm and exit.
169 -l
171 --line-numbers
172 For each symbol, use debugging information to try to find a
173 filename and line number. For a defined symbol, look for the line
174 number of the address of the symbol. For an undefined symbol, look
175 for the line number of a relocation entry which refers to the
176 symbol. If line number information can be found, print it after
177 the other symbol information.
178 --inlines
180 When option -l is active, if the address belongs to a function that
181 was inlined, then this option causes the source information for all
182 enclosing scopes back to the first non-inlined function to be
183 printed as well. For example, if "main" inlines "callee1" which
184 inlines "callee2", and address is from "callee2", the source
185 information for "callee1" and "main" will also be printed.
186 -n
188 -v
189 --numeric-sort
190 Sort symbols numerically by their addresses, rather than
191 alphabetically by their names.
192 -p
194 --no-sort
195 Do not bother to sort the symbols in any order; print them in the
196 order encountered.
197 -P
199 --portability
200 Use the POSIX.2 standard output format instead of the default
201 format. Equivalent to -f posix.
202 -r
204 --reverse-sort
205 Reverse the order of the sort (whether numeric or alphabetic); let
206 the last come first.
207 -S
209 --print-size
210 Print both value and size of defined symbols for the "bsd" output
211 style. This option has no effect for object formats that do not
212 record symbol sizes, unless --size-sort is also used in which case
213 a calculated size is displayed.
214 -s
216 --print-armap
217 When listing symbols from archive members, include the index: a
218 mapping (stored in the archive by ar or ranlib) of which modules
219 contain definitions for which names.
220 -t radix
222 --radix=radix
223 Use radix as the radix for printing the symbol values. It must be
224 d for decimal, o for octal, or x for hexadecimal.
225 -u
227 --undefined-only
228 Display only undefined symbols (those external to each object
229 file).
230 -V
232 --version
233 Show the version number of nm and exit.
234 -X This option is ignored for compatibility with the AIX version of
236 nm. It takes one parameter which must be the string 32_64. The
237 default mode of AIX nm corresponds to -X 32, which is not supported
238 by GNU nm.
239 --defined-only
241 Display only defined symbols for each object file.
242 --plugin name
244 Load the plugin called name to add support for extra target types.
245 This option is only available if the toolchain has been built with
246 plugin support enabled.
247 If --plugin is not provided, but plugin support has been enabled
249 then nm iterates over the files in ${libdir}/bfd-plugins in
250 alphabetic order and the first plugin that claims the object in
251 question is used.
252 Please note that this plugin search directory is not the one used
254 by ld's -plugin option. In order to make nm use the linker plugin
255 it must be copied into the ${libdir}/bfd-plugins directory. For
256 GCC based compilations the linker plugin is called
257 liblto_plugin.so.0.0.0. For Clang based compilations it is called
258 LLVMgold.so. The GCC plugin is always backwards compatible with
259 earlier versions, so it is sufficient to just copy the newest one.
260 --size-sort
262 Sort symbols by size. For ELF objects symbol sizes are read from
263 the ELF, for other object types the symbol sizes are computed as
264 the difference between the value of the symbol and the value of the
265 symbol with the next higher value. If the "bsd" output format is
266 used the size of the symbol is printed, rather than the value, and
267 -S must be used in order both size and value to be printed.
268 --special-syms
270 Display symbols which have a target-specific special meaning.
271 These symbols are usually used by the target for some special
272 processing and are not normally helpful when included in the normal
273 symbol lists. For example for ARM targets this option would skip
274 the mapping symbols used to mark transitions between ARM code,
275 THUMB code and data.
276 --synthetic
278 Include synthetic symbols in the output. These are special symbols
279 created by the linker for various purposes. They are not shown by
280 default since they are not part of the binary's original source
281 code.
282 --with-symbol-versions
284 Enables the display of symbol version information if any exists.
285 The version string is displayed as a suffix to the symbol name,
286 preceeded by an @ character. For example foo@VER_1. If the
287 version is the default version to be used when resolving
288 unversioned references to the symbol then it is displayed as a
289 suffix preceeded by two @ characters. For example foo@@VER_2.
290 --target=bfdname
292 Specify an object code format other than your system's default
293 format.
294 @file
296 Read command-line options from file. The options read are inserted
297 in place of the original @file option. If file does not exist, or
298 cannot be read, then the option will be treated literally, and not
299 removed.
300 Options in file are separated by whitespace. A whitespace
302 character may be included in an option by surrounding the entire
303 option in either single or double quotes. Any character (including
304 a backslash) may be included by prefixing the character to be
305 included with a backslash. The file may itself contain additional
306 @file options; any such options will be processed recursively.
307
309 ar(1), objdump(1), ranlib(1), and the Info entries for binutils.
310
312 Copyright (c) 1991-2018 Free Software Foundation, Inc.
313 Permission is granted to copy, distribute and/or modify this document
315 under the terms of the GNU Free Documentation License, Version 1.3 or
316 any later version published by the Free Software Foundation; with no
317 Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
318 Texts. A copy of the license is included in the section entitled "GNU
319 Free Documentation License".
320binutils-2.30.90 2018-07-09 NM(1)