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PROLOG | NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | STDIN | INPUT FILES | ENVIRONMENT VARIABLES | ASYNCHRONOUS EVENTS | STDOUT | STDERR | OUTPUT FILES | EXTENDED DESCRIPTION | EXIT STATUS | CONSEQUENCES OF ERRORS | APPLICATION USAGE | EXAMPLES | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
NM(1P) POSIX Programmer's Manual NM(1P)
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior), or
the interface may not be implemented on Linux.
nm — write the name list of an object file (DEVELOPMENT)
nm [−APv] [−g|−u] [−t format] file...
nm [−APv] [−efox] [−g|−u] [−t format] file...
The nm utility shall display symbolic information appearing in the
object file, executable file, or object-file library named by file.
If no symbolic information is available for a valid input file, the
nm utility shall report that fact, but not consider it an error
condition.
The default base used when numeric values are written is unspecified.
On XSI-conformant systems, it shall be decimal.
The nm utility shall conform to the Base Definitions volume of
POSIX.1‐2008, Section 12.2, Utility Syntax Guidelines.
The following options shall be supported:
−A Write the full pathname or library name of an object on
each line.
−e Write only external (global) and static symbol information.
−f Produce full output. Write redundant symbols (.text, .data,
and .bss), normally suppressed.
−g Write only external (global) symbol information.
−o Write numeric values in octal (equivalent to −t o).
−P Write information in a portable output format, as specified
in the STDOUT section.
−t format Write each numeric value in the specified format. The
format shall be dependent on the single character used as
the format option-argument:
d The offset is written in decimal (default).
o The offset is written in octal.
x The offset is written in hexadecimal.
−u Write only undefined symbols.
−v Sort output by value instead of by symbol name.
−x Write numeric values in hexadecimal (equivalent to −t x).
The following operand shall be supported:
file A pathname of an object file, executable file, or object-
file library.
See the INPUT FILES section.
The input file shall be an object file, an object-file library whose
format is the same as those produced by the ar utility for link
editing, or an executable file. The nm utility may accept additional
implementation-defined object library formats for the input file.
The following environment variables shall affect the execution of nm:
LANG Provide a default value for the internationalization
variables that are unset or null. (See the Base Definitions
volume of POSIX.1‐2008, Section 8.2, Internationalization
Variables for the precedence of internationalization
variables used to determine the values of locale
categories.)
LC_ALL If set to a non-empty string value, override the values of
all the other internationalization variables.
LC_COLLATE
Determine the locale for character collation information
for the symbol-name and symbol-value collation sequences.
LC_CTYPE Determine the locale for the interpretation of sequences of
bytes of text data as characters (for example, single-byte
as opposed to multi-byte characters in arguments).
LC_MESSAGES
Determine the locale that should be used to affect the
format and contents of diagnostic messages written to
standard error.
NLSPATH Determine the location of message catalogs for the
processing of LC_MESSAGES.
Default.
If symbolic information is present in the input files, then for each
file or for each member of an archive, the nm utility shall write the
following information to standard output. By default, the format is
unspecified, but the output shall be sorted by symbol name according
to the collation sequence in the current locale.
* Library or object name, if −A is specified
* Symbol name
* Symbol type, which shall either be one of the following single
characters or an implementation-defined type represented by a
single character:
A Global absolute symbol.
a Local absolute symbol.
B Global ``bss'' (that is, uninitialized data space) symbol.
b Local bss symbol.
D Global data symbol.
d Local data symbol.
T Global text symbol.
t Local text symbol.
U Undefined symbol.
* Value of the symbol
* The size associated with the symbol, if applicable
This information may be supplemented by additional information
specific to the implementation.
If the −P option is specified, the previous information shall be
displayed using the following portable format. The three versions
differ depending on whether −t d, −t o, or −t x was specified,
respectively:
"%s%s %s %d %d\n", <library/object name>, <name>, <type>,
<value>, <size>
"%s%s %s %o %o\n", <library/object name>, <name>, <type>,
<value>, <size>
"%s%s %s %x %x\n", <library/object name>, <name>, <type>,
<value>, <size>
where <library/object name> shall be formatted as follows:
* If −A is not specified, <library/object name> shall be an empty
string.
* If −A is specified and the corresponding file operand does not
name a library:
"%s: ", <file>
* If −A is specified and the corresponding file operand names a
library. In this case, <object file> shall name the object file
in the library containing the symbol being described:
"%s[%s]: ", <file>, <object file>
If −A is not specified, then if more than one file operand is
specified or if only one file operand is specified and it names a
library, nm shall write a line identifying the object containing the
following symbols before the lines containing those symbols, in the
form:
* If the corresponding file operand does not name a library:
"%s:\n", <file>
* If the corresponding file operand names a library; in this case,
<object file> shall be the name of the file in the library
containing the following symbols:
"%s[%s]:\n", <file>, <object file>
If −P is specified, but −t is not, the format shall be as if −t x had
been specified.
The standard error shall be used only for diagnostic messages.
None.
None.
The following exit values shall be returned:
0 Successful completion.
>0 An error occurred.
Default.
The following sections are informative.
Mechanisms for dynamic linking make this utility less meaningful when
applied to an executable file because a dynamically linked executable
may omit numerous library routines that would be found in a
statically linked executable.
None.
Historical implementations of nm have used different bases for
numeric output and supplied different default types of symbols that
were reported. The −t format option, similar to that used in od and
strings, can be used to specify the numeric base; −g and −u can be
used to restrict the amount of output or the types of symbols
included in the output.
The compromise of using −t format versus using −d, −o, and other
similar options was necessary because of differences in the meaning
of −o between implementations. The −o option from BSD has been
provided here as −A to avoid confusion with the −o from System V
(which has been provided here as −t and as −o on XSI-conformant
systems).
The option list was significantly reduced from that provided by
historical implementations.
The nm description is a subset of both the System V and BSD nm
utilities with no specified default output.
It was recognized that mechanisms for dynamic linking make this
utility less meaningful when applied to an executable file (because a
dynamically linked executable file may omit numerous library routines
that would be found in a statically linked executable file), but the
value of nm during software development was judged to outweigh other
limitations.
The default output format of nm is not specified because of
differences in historical implementations. The −P option was added
to allow some type of portable output format. After a comparison of
the different formats used in SunOS, BSD, SVR3, and SVR4, it was
decided to create one that did not match the current format of any of
these four systems. The format devised is easy to parse by humans,
easy to parse in shell scripts, and does not need to vary depending
on locale (because no English descriptions are included). All of the
systems currently have the information available to use this format.
The format given in nm STDOUT uses <space> characters between the
fields, which may be any number of <blank> characters required to
align the columns. The single-character types were selected to match
historical practice, and the requirement that implementation
additions also be single characters made parsing the information
easier for shell scripts.
None.
ar(1p), c99(1p)
The Base Definitions volume of POSIX.1‐2008, Chapter 8, Environment
Variables, Section 12.2, Utility Syntax Guidelines
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) In the event of any discrepancy between this version and
the original IEEE and The Open Group Standard, the original IEEE and
The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the
source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 NM(1P)
Pages that refer to this page: c99(1p), strings(1p)