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Linux 2.6 - man page for nm (linux section 1posix)

NM(P)				    POSIX Programmer's Manual				    NM(P)

       nm - write the name list of an object file (DEVELOPMENT)

       nm [-APv][-efox][ -g| -u][-t format] file...

       This utility shall be provided on systems that support both the User Portability Utilities
       option and the Software Development Utilities option. On other  systems	it  is	optional.
       Certain options are only available on XSI-conformant systems.

       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 con-

       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 IEEE Std 1003.1-2001, Sec-
       tion 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

       -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:

	      The offset is written in decimal	  (default).

	      The offset is written in octal.

	      The offset is written in hexadecimal.

       -u     Write only undefined symbols.

       -v     Sort output by value instead of alphabetically.

       -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 IEEE Std 1003.1-2001, Section 8.2, Inter-
	      nationalization 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 interna-
	      tionalization variables.


	      Determine the locale for character collation information for  the  symbol-name  and
	      symbol-value collation sequences.

	      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  argu-

	      Determine the locale that should be used to affect the format and contents of diag-
	      nostic messages written to standard error.

	      Determine the location of message catalogs for the processing of LC_MESSAGES .


       If symbolic information is present in the input files, then for each file or for each mem-
       ber  of	an archive, the nm utility shall write the following information to standard out-
       put.  By default, the format is unspecified, but the output shall be sorted alphabetically
       by symbol name:

	* Library or object name, if -A is specified

	* Symbol name

	* Symbol  type, which shall either be one of the following single characters or an imple-
	  mentation-defined type represented by a single character:

	      Global absolute symbol.

	      Local absolute symbol.

	      Global "bss" (that is, uninitialized data space) symbol.

	      Local bss symbol.

	      Global data symbol.

	      Local data symbol.

	      Global text symbol.

	      Local text symbol.

	      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 implementa-

       If  the -P option is specified, the previous information shall be displayed using the fol-
       lowing 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

	  "%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

	* 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.



       The following exit values shall be returned:

	0     Successful completion.

       >0     An error occurred.


       The following sections are informative.

       Mechanisms  for	dynamic linking make this utility less meaningful when applied to an exe-
       cutable file because a dynamically linked executable may omit  numerous	library  routines
       that would be found in a statically linked executable.


       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  nec-
       essary  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 implementa-

       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 spaces between the fields, which may be any  number  of
       <blank>s  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.


       ar , c99

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1, 2003 Edition, Standard for Information Technology  --  Portable	Operating  System
       Interface  (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by
       the Institute of Electrical and Electronics Engineers, Inc and  The  Open  Group.  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 orig-
       inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group			       2003					    NM(P)

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