nm






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 utility shall display symbolic information appearing in
the object file, executable file, or object‐file library
named by If no symbolic information is available for a valid
input file, the 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 utility shall conform to the Base Definitions volume of
POSIX.1‐2008, 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 (and
          normally suppressed.

−g        Write only external (global) symbol information.

−o        Write numeric values in octal (equivalent to

−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 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.











                             ‐2‐


−v        Sort output by value instead of by symbol name.

−x        Write numeric values in hexadecimal (equivalent to

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
utility for link editing, or an executable file. The utility
may accept additional implementation‐defined object library
formats for the input file.

The following environment variables shall affect the
execution of

LANG      Provide a default value for the
          internationalization variables that are unset or
          null. (See the Base Definitions volume of
          POSIX.1‐2008, 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

Default.













                             ‐3‐


If symbolic information is present in the input files, then
for each file or for each member of an archive, the 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 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
    option is specified, the previous information shall be
    displayed using the following portable format. The three
    versions differ depending on whether or 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:











                             ‐4‐


 *  If is not specified, <library/object name> shall be an
    empty string.

 *  If is specified and the corresponding operand does not
    name a library:

             "%s: ", <file>

 *  If is specified and the corresponding 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 is not specified, then if more than one operand is
    specified or if only one operand is specified and it
    names a library, shall write a line identifying the
    object containing the following symbols before the lines
    containing those symbols, in the form:

 *  If the corresponding operand does not name a library:

             "%s:\n", <file>

 *  If the corresponding 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 is specified, but is not, the format shall be as if
    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.


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.










                             ‐5‐


None.

Historical implementations of have used different bases for
numeric output and supplied different default types of
symbols that were reported. The option, similar to that used
in and can be used to specify the numeric base; and can be
used to restrict the amount of output or the types of
symbols included in the output.  The compromise of using
versus using and other similar options was necessary because
of differences in the meaning of between implementations.
The option from BSD has been provided here as to avoid
confusion with the from System V (which has been provided
here as and as on XSI‐conformant systems).  The option list
was significantly reduced from that provided by historical
implementations.  The description is a subset of both the
System V and BSD 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 during
software development was judged to outweigh other
limitations.  The default output format of is not specified
because of differences in historical implementations.  The
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 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.

The Base Definitions volume of POSIX.1‐2008,

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









                             ‐6‐


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 .