1NM(1P) POSIX Programmer's Manual NM(1P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
13 nm — write the name list of an object file (DEVELOPMENT)
14
16 nm [−APv] [−g|−u] [−t format] file...
17 nm [−APv] [−efox] [−g|−u] [−t format] file...
18
20 The nm utility shall display symbolic information appearing in the
21 object file, executable file, or object-file library named by file. If
22 no symbolic information is available for a valid input file, the nm
23 utility shall report that fact, but not consider it an error condition.
24 The default base used when numeric values are written is unspecified.
26 On XSI-conformant systems, it shall be decimal.
27
29 The nm utility shall conform to the Base Definitions volume of
30 POSIX.1‐2008, Section 12.2, Utility Syntax Guidelines.
31 The following options shall be supported:
33 −A Write the full pathname or library name of an object on each
35 line.
36 −e Write only external (global) and static symbol information.
38 −f Produce full output. Write redundant symbols (.text, .data,
40 and .bss), normally suppressed.
41 −g Write only external (global) symbol information.
43 −o Write numeric values in octal (equivalent to −t o).
45 −P Write information in a portable output format, as specified
47 in the STDOUT section.
48 −t format Write each numeric value in the specified format. The format
50 shall be dependent on the single character used as the format
51 option-argument:
52 d The offset is written in decimal (default).
54 o The offset is written in octal.
56 x The offset is written in hexadecimal.
58 −u Write only undefined symbols.
60 −v Sort output by value instead of by symbol name.
62 −x Write numeric values in hexadecimal (equivalent to −t x).
64
66 The following operand shall be supported:
67 file A pathname of an object file, executable file, or object-file
69 library.
70
72 See the INPUT FILES section.
73
75 The input file shall be an object file, an object-file library whose
76 format is the same as those produced by the ar utility for link edit‐
77 ing, or an executable file. The nm utility may accept additional imple‐
78 mentation-defined object library formats for the input file.
79
81 The following environment variables shall affect the execution of nm:
82 LANG Provide a default value for the internationalization vari‐
84 ables that are unset or null. (See the Base Definitions vol‐
85 ume of POSIX.1‐2008, Section 8.2, Internationalization Vari‐
86 ables for the precedence of internationalization variables
87 used to determine the values of locale categories.)
88 LC_ALL If set to a non-empty string value, override the values of
90 all the other internationalization variables.
91 LC_COLLATE
93 Determine the locale for character collation information for
94 the symbol-name and symbol-value collation sequences.
95 LC_CTYPE Determine the locale for the interpretation of sequences of
97 bytes of text data as characters (for example, single-byte as
98 opposed to multi-byte characters in arguments).
99 LC_MESSAGES
101 Determine the locale that should be used to affect the format
102 and contents of diagnostic messages written to standard
103 error.
104 NLSPATH Determine the location of message catalogs for the processing
106 of LC_MESSAGES.
107
109 Default.
110
112 If symbolic information is present in the input files, then for each
113 file or for each member of an archive, the nm utility shall write the
114 following information to standard output. By default, the format is
115 unspecified, but the output shall be sorted by symbol name according to
116 the collation sequence in the current locale.
117 * Library or object name, if −A is specified
119 * Symbol name
121 * Symbol type, which shall either be one of the following single
123 characters or an implementation-defined type represented by a sin‐
124 gle character:
125 A Global absolute symbol.
127 a Local absolute symbol.
129 B Global ``bss'' (that is, uninitialized data space) symbol.
131 b Local bss symbol.
133 D Global data symbol.
135 d Local data symbol.
137 T Global text symbol.
139 t Local text symbol.
141 U Undefined symbol.
143 * Value of the symbol
145 * The size associated with the symbol, if applicable
147 This information may be supplemented by additional information specific
149 to the implementation.
150 If the −P option is specified, the previous information shall be dis‐
152 played using the following portable format. The three versions differ
153 depending on whether −t d, −t o, or −t x was specified, respectively:
154 "%s%s %s %d %d\n", <library/object name>, <name>, <type>,
156 <value>, <size>
157 "%s%s %s %o %o\n", <library/object name>, <name>, <type>,
159 <value>, <size>
160 "%s%s %s %x %x\n", <library/object name>, <name>, <type>,
162 <value>, <size>
163 where <library/object name> shall be formatted as follows:
165 * If −A is not specified, <library/object name> shall be an empty
167 string.
168 * If −A is specified and the corresponding file operand does not name
170 a library:
171 "%s: ", <file>
173 * If −A is specified and the corresponding file operand names a
175 library. In this case, <object file> shall name the object file in
176 the library containing the symbol being described:
177 "%s[%s]: ", <file>, <object file>
179 If −A is not specified, then if more than one file operand is specified
181 or if only one file operand is specified and it names a library, nm
182 shall write a line identifying the object containing the following sym‐
183 bols before the lines containing those symbols, in the form:
184 * If the corresponding file operand does not name a library:
186 "%s:\n", <file>
188 * If the corresponding file operand names a library; in this case,
190 <object file> shall be the name of the file in the library contain‐
191 ing the following symbols:
192 "%s[%s]:\n", <file>, <object file>
194 If −P is specified, but −t is not, the format shall be as if −t x had
196 been specified.
197
199 The standard error shall be used only for diagnostic messages.
200
202 None.
203
205 None.
206
208 The following exit values shall be returned:
209 0 Successful completion.
211 >0 An error occurred.
213
215 Default.
216 The following sections are informative.
218
220 Mechanisms for dynamic linking make this utility less meaningful when
221 applied to an executable file because a dynamically linked executable
222 may omit numerous library routines that would be found in a statically
223 linked executable.
224
226 None.
227
229 Historical implementations of nm have used different bases for numeric
230 output and supplied different default types of symbols that were
231 reported. The −t format option, similar to that used in od and strings,
232 can be used to specify the numeric base; −g and −u can be used to
233 restrict the amount of output or the types of symbols included in the
234 output.
235 The compromise of using −t format versus using −d, −o, and other simi‐
237 lar options was necessary because of differences in the meaning of −o
238 between implementations. The −o option from BSD has been provided here
239 as −A to avoid confusion with the −o from System V (which has been pro‐
240 vided here as −t and as −o on XSI-conformant systems).
241 The option list was significantly reduced from that provided by histor‐
243 ical implementations.
244 The nm description is a subset of both the System V and BSD nm utili‐
246 ties with no specified default output.
247 It was recognized that mechanisms for dynamic linking make this utility
249 less meaningful when applied to an executable file (because a dynami‐
250 cally linked executable file may omit numerous library routines that
251 would be found in a statically linked executable file), but the value
252 of nm during software development was judged to outweigh other limita‐
253 tions.
254 The default output format of nm is not specified because of differences
256 in historical implementations. The −P option was added to allow some
257 type of portable output format. After a comparison of the different
258 formats used in SunOS, BSD, SVR3, and SVR4, it was decided to create
259 one that did not match the current format of any of these four systems.
260 The format devised is easy to parse by humans, easy to parse in shell
261 scripts, and does not need to vary depending on locale (because no Eng‐
262 lish descriptions are included). All of the systems currently have the
263 information available to use this format.
264 The format given in nm STDOUT uses <space> characters between the
266 fields, which may be any number of <blank> characters required to align
267 the columns. The single-character types were selected to match histori‐
268 cal practice, and the requirement that implementation additions also be
269 single characters made parsing the information easier for shell
270 scripts.
271
273 None.
274
276 ar, c99
277 The Base Definitions volume of POSIX.1‐2008, Chapter 8, Environment
279 Variables, Section 12.2, Utility Syntax Guidelines
280
282 Portions of this text are reprinted and reproduced in electronic form
283 from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
284 -- Portable Operating System Interface (POSIX), The Open Group Base
285 Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
286 cal and Electronics Engineers, Inc and The Open Group. (This is
287 POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
288 event of any discrepancy between this version and the original IEEE and
289 The Open Group Standard, the original IEEE and The Open Group Standard
290 is the referee document. The original Standard can be obtained online
291 at http://www.unix.org/online.html .
292 Any typographical or formatting errors that appear in this page are
294 most likely to have been introduced during the conversion of the source
295 files to man page format. To report such errors, see https://www.ker‐
296 nel.org/doc/man-pages/reporting_bugs.html .
297IEEE/The Open Group 2013 NM(1P)