1NM(1) GNU Development Tools NM(1)
2
6 nm - list symbols from object files
7
9 nm [-a|--debug-syms] [-g|--extern-only]
10 [-B] [-C|--demangle[=style]] [-D|--dynamic]
11 [-S|--print-size] [-s|--print-armap]
12 [-A|-o|--print-file-name][--special-syms]
13 [-n|-v|--numeric-sort] [-p|--no-sort]
14 [-r|--reverse-sort] [--size-sort] [-u|--undefined-only]
15 [-t radix|--radix=radix] [-P|--portability]
16 [--target=bfdname] [-fformat|--format=format]
17 [--defined-only] [-l|--line-numbers] [--no-demangle]
18 [-V|--version] [-X 32_64] [--help] [objfile...]
19
21 GNU nm lists the symbols from object files objfile.... If no object
22 files are listed as arguments, nm assumes the file a.out.
23 For each symbol, nm shows:
25 · The symbol value, in the radix selected by options (see below), or
27 hexadecimal by default.
28 · The symbol type. At least the following types are used; others
30 are, as well, depending on the object file format. If lowercase,
31 the symbol is local; if uppercase, the symbol is global (external).
32 "A" The symbol's value is absolute, and will not be changed by fur‐
34 ther linking.
35 "B" The symbol is in the uninitialized data section (known as BSS).
37 "C" The symbol is common. Common symbols are uninitialized data.
39 When linking, multiple common symbols may appear with the same
40 name. If the symbol is defined anywhere, the common symbols
41 are treated as undefined references.
42 "D" The symbol is in the initialized data section.
44 "G" The symbol is in an initialized data section for small objects.
46 Some object file formats permit more efficient access to small
47 data objects, such as a global int variable as opposed to a
48 large global array.
49 "I" The symbol is an indirect reference to another symbol. This is
51 a GNU extension to the a.out object file format which is rarely
52 used.
53 "N" The symbol is a debugging symbol.
55 "R" The symbol is in a read only data section.
57 "S" The symbol is in an uninitialized data section for small
59 objects.
60 "T" The symbol is in the text (code) section.
62 "U" The symbol is undefined.
64 "V" The symbol is a weak object. When a weak defined symbol is
66 linked with a normal defined symbol, the normal defined symbol
67 is used with no error. When a weak undefined symbol is linked
68 and the symbol is not defined, the value of the weak symbol
69 becomes zero with no error.
70 "W" The symbol is a weak symbol that has not been specifically
72 tagged as a weak object symbol. When a weak defined symbol is
73 linked with a normal defined symbol, the normal defined symbol
74 is used with no error. When a weak undefined symbol is linked
75 and the symbol is not defined, the value of the symbol is
76 determined in a system-specific manner without error. On some
77 systems, uppercase indicates that a default value has been
78 specified.
79 "-" The symbol is a stabs symbol in an a.out object file. In this
81 case, the next values printed are the stabs other field, the
82 stabs desc field, and the stab type. Stabs symbols are used to
83 hold debugging information.
84 "?" The symbol type is unknown, or object file format specific.
86 · The symbol name.
88
90 The long and short forms of options, shown here as alternatives, are
91 equivalent.
92 -A
94 -o
95 --print-file-name
96 Precede each symbol by the name of the input file (or archive mem‐
97 ber) in which it was found, rather than identifying the input file
98 once only, before all of its symbols.
99 -a
101 --debug-syms
102 Display all symbols, even debugger-only symbols; normally these are
103 not listed.
104 -B The same as --format=bsd (for compatibility with the MIPS nm).
106 -C
108 --demangle[=style]
109 Decode (demangle) low-level symbol names into user-level names.
110 Besides removing any initial underscore prepended by the system,
111 this makes C++ function names readable. Different compilers have
112 different mangling styles. The optional demangling style argument
113 can be used to choose an appropriate demangling style for your com‐
114 piler.
115 --no-demangle
117 Do not demangle low-level symbol names. This is the default.
118 -D
120 --dynamic
121 Display the dynamic symbols rather than the normal symbols. This
122 is only meaningful for dynamic objects, such as certain types of
123 shared libraries.
124 -f format
126 --format=format
127 Use the output format format, which can be "bsd", "sysv", or
128 "posix". The default is "bsd". Only the first character of format
129 is significant; it can be either upper or lower case.
130 -g
132 --extern-only
133 Display only external symbols.
134 -l
136 --line-numbers
137 For each symbol, use debugging information to try to find a file‐
138 name and line number. For a defined symbol, look for the line num‐
139 ber of the address of the symbol. For an undefined symbol, look
140 for the line number of a relocation entry which refers to the sym‐
141 bol. If line number information can be found, print it after the
142 other symbol information.
143 -n
145 -v
146 --numeric-sort
147 Sort symbols numerically by their addresses, rather than alphabeti‐
148 cally by their names.
149 -p
151 --no-sort
152 Do not bother to sort the symbols in any order; print them in the
153 order encountered.
154 -P
156 --portability
157 Use the POSIX.2 standard output format instead of the default for‐
158 mat. Equivalent to -f posix.
159 -S
161 --print-size
162 Print size, not the value, of defined symbols for the "bsd" output
163 format.
164 -s
166 --print-armap
167 When listing symbols from archive members, include the index: a
168 mapping (stored in the archive by ar or ranlib) of which modules
169 contain definitions for which names.
170 -r
172 --reverse-sort
173 Reverse the order of the sort (whether numeric or alphabetic); let
174 the last come first.
175 --size-sort
177 Sort symbols by size. The size is computed as the difference
178 between the value of the symbol and the value of the symbol with
179 the next higher value. If the "bsd" output format is used the size
180 of the symbol is printed, rather than the value, and -S must be
181 used in order both size and value to be printed.
182 --special-syms
184 Display symbols which have a target-specific special meaning.
185 These symbols are usually used by the target for some special pro‐
186 cessing and are not normally helpful when included included in the
187 normal symbol lists. For example for ARM targets this option would
188 skip the mapping symbols used to mark transistions between ARM
189 code, THUMB code and data.
190 -t radix
192 --radix=radix
193 Use radix as the radix for printing the symbol values. It must be
194 d for decimal, o for octal, or x for hexadecimal.
195 --target=bfdname
197 Specify an object code format other than your system's default for‐
198 mat.
199 -u
201 --undefined-only
202 Display only undefined symbols (those external to each object
203 file).
204 --defined-only
206 Display only defined symbols for each object file.
207 -V
209 --version
210 Show the version number of nm and exit.
211 -X This option is ignored for compatibility with the AIX version of
213 nm. It takes one parameter which must be the string 32_64. The
214 default mode of AIX nm corresponds to -X 32, which is not supported
215 by GNU nm.
216 --help
218 Show a summary of the options to nm and exit.
219 @file
221 Read command-line options from file. The options read are inserted
222 in place of the original @file option. If file does not exist, or
223 cannot be read, then the option will be treated literally, and not
224 removed.
225 Options in file are separated by whitespace. A whitespace charac‐
227 ter may be included in an option by surrounding the entire option
228 in either single or double quotes. Any character (including a
229 backslash) may be included by prefixing the character to be
230 included with a backslash. The file may itself contain additional
231 @file options; any such options will be processed recursively.
232
234 ar(1), objdump(1), ranlib(1), and the Info entries for binutils.
235
237 Copyright (c) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
238 2000, 2001, 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
239 Permission is granted to copy, distribute and/or modify this document
241 under the terms of the GNU Free Documentation License, Version 1.1 or
242 any later version published by the Free Software Foundation; with no
243 Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
244 Texts. A copy of the license is included in the section entitled "GNU
245 Free Documentation License".
246binutils-2.17 2006-06-23 NM(1)