GETCONF(1P)		   POSIX Programmer's Manual		   GETCONF(1P)



PROLOG
       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.


NAME
       getconf -- get configuration values

SYNOPSIS
       getconf [-v specification] system_var

       getconf [-v specification] path_var pathname

DESCRIPTION
       In the first synopsis form, the getconf	utility	 shall	write  to  the
       standard	 output	 the value of the variable specified by the system_var
       operand.

       In the second synopsis form, the getconf utility	 shall	write  to  the
       standard output the value of the variable specified by the path_var op-
       erand for the path specified by the pathname operand.

       The value of each configuration variable shall be determined as	if  it
       were  obtained  by  calling the function from which it is defined to be
       available by this volume of POSIX.1-2008 or by  the  System  Interfaces
       volume  of  POSIX.1-2008	 (see  the  OPERANDS section). The value shall
       reflect conditions in the current operating environment.

OPTIONS
       The getconf utility shall conform to the	 Base  Definitions  volume  of
       POSIX.1-2008, Section 12.2, Utility Syntax Guidelines.

       The following option shall be supported:

       -v specification
		 Indicate  a specific specification and version for which con-
		 figuration variables shall be determined. If this  option  is
		 not specified, the values returned correspond to an implemen-
		 tation default conforming compilation environment.

		 If the command:

		     getconf _POSIX_V7_ILP32_OFF32

		 does not write "-1\n" or "undefined\n"	 to  standard  output,
		 then commands of the form:

		     getconf -v POSIX_V7_ILP32_OFF32 ...

		 determine values for configuration variables corresponding to
		 the POSIX_V7_ILP32_OFF32 compilation environment specified in
		 c99, the EXTENDED DESCRIPTION.

		 If the command:

		     getconf _POSIX_V7_ILP32_OFFBIG

		 does  not  write  "-1\n" or "undefined\n" to standard output,
		 then commands of the form:

		     getconf -v POSIX_V7_ILP32_OFFBIG ...

		 determine values for configuration variables corresponding to
		 the  POSIX_V7_ILP32_OFFBIG  compilation environment specified
		 in c99, the EXTENDED DESCRIPTION.

		 If the command:

		     getconf _POSIX_V7_LP64_OFF64

		 does not write "-1\n" or "undefined\n"	 to  standard  output,
		 then commands of the form:

		     getconf -v POSIX_V7_LP64_OFF64 ...

		 determine values for configuration variables corresponding to
		 the POSIX_V7_LP64_OFF64 compilation environment specified  in
		 c99, the EXTENDED DESCRIPTION.

		 If the command:

		     getconf _POSIX_V7_LPBIG_OFFBIG

		 does  not  write  "-1\n" or "undefined\n" to standard output,
		 then commands of the form:

		     getconf -v POSIX_V7_LPBIG_OFFBIG ...

		 determine values for configuration variables corresponding to
		 the  POSIX_V7_LPBIG_OFFBIG  compilation environment specified
		 in c99, the EXTENDED DESCRIPTION.

OPERANDS
       The following operands shall be supported:

       path_var	 A name of a configuration variable. All of the	 variables  in
		 the  Variable	column	of the table in the DESCRIPTION of the
		 fpathconf() function defined in the System Interfaces	volume
		 of  POSIX.1-2008, without the enclosing braces, shall be sup-
		 ported. The implementation may add other local variables.

       pathname	 A pathname for which the variable specified by path_var is to
		 be determined.

       system_var
		 A  name  of  a	 configuration	variable. All of the following
		 variables shall be supported:

		  *  The names in the Variable column  of  the	table  in  the
		     DESCRIPTION  of  the  sysconf()  function	in  the System
		     Interfaces volume of POSIX.1-2008, except for the entries
		     corresponding  to	_SC_CLK_TCK, _SC_GETGR_R_SIZE_MAX, and
		     _SC_GETPW_R_SIZE_MAX, without the enclosing braces.

		     For compatibility with earlier  versions,	the  following
		     variable  names  shall  also  be supported: POSIX2_C_BIND
		     POSIX2_C_DEV	POSIX2_CHAR_TERM       POSIX2_FORT_DEV
		     POSIX2_FORT_RUN POSIX2_LOCALEDEF POSIX2_SW_DEV POSIX2_UPE
		     POSIX2_VERSION

		     and shall be equivalent to the same name prefixed with an
		     <underscore>.   This  requirement	may  be	 removed  in a
		     future version.

		  *  The names of the symbolic	constants  used	 as  the  name
		     argument  of  the confstr() function in the System Inter-
		     faces volume of POSIX.1-2008, without the _CS_ prefix.

		  *  The names of the  symbolic	 constants  listed  under  the
		     headings ``Maximum Values'' and ``Minimum Values'' in the
		     description of the <limits.h> header in the Base  Defini-
		     tions  volume  of	POSIX.1-2008,  without	the  enclosing
		     braces.

		     For compatibility with earlier  versions,	the  following
		     variable	  names	    shall     also    be    supported:
		     POSIX2_BC_BASE_MAX POSIX2_BC_DIM_MAX  POSIX2_BC_SCALE_MAX
		     POSIX2_BC_STRING_MAX	       POSIX2_COLL_WEIGHTS_MAX
		     POSIX2_EXPR_NEST_MAX POSIX2_LINE_MAX POSIX2_RE_DUP_MAX

		     and shall be equivalent to the same name prefixed with an
		     <underscore>.   This  requirement	may  be	 removed  in a
		     future version.

		 The implementation may add other local values.

STDIN
       Not used.

INPUT FILES
       None.

ENVIRONMENT VARIABLES
       The following environment variables shall affect the execution of  get-
       conf:

       LANG	 Provide  a  default  value for the internationalization vari-
		 ables that are unset or null. (See the Base Definitions  vol-
		 ume  of POSIX.1-2008, Section 8.2, Internationalization Vari-
		 ables 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_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.

ASYNCHRONOUS EVENTS
       Default.

STDOUT
       If  the	specified  variable  is defined on the system and its value is
       described to be available from the confstr() function  defined  in  the
       System Interfaces volume of POSIX.1-2008, its value shall be written in
       the following format:

	   "%s\n", <value>

       Otherwise, if the specified variable is	defined	 on  the  system,  its
       value shall be written in the following format:

	   "%d\n", <value>

       If  the	specified  variable  is valid, but is undefined on the system,
       getconf shall write using the following format:

	   "undefined\n"

       If the variable name is invalid or an error occurs,  nothing  shall  be
       written to standard output.

STDERR
       The standard error shall be used only for diagnostic messages.

OUTPUT FILES
       None.

EXTENDED DESCRIPTION
       None.

EXIT STATUS
       The following exit values shall be returned:

	0    The specified variable is valid and information about its current
	     state was written successfully.

       >0    An error occurred.

CONSEQUENCES OF ERRORS
       Default.

       The following sections are informative.

APPLICATION USAGE
       None.

EXAMPLES
       The following example illustrates the value of {NGROUPS_MAX}:

	   getconf NGROUPS_MAX

       The following example illustrates the value of {NAME_MAX}  for  a  spe-
       cific directory:

	   getconf NAME_MAX /usr

       The  following  example	shows  how to deal more carefully with results
       that might be unspecified:

	   if value=$(getconf PATH_MAX /usr); then
	       if [ "$value" = "undefined" ]; then
		   echo PATH_MAX in /usr is indeterminate.
	       else
		   echo PATH_MAX in /usr is $value.
	       fi
	   else
	       echo Error in getconf.
	   fi

RATIONALE
       The original need for this utility, and for the confstr() function, was
       to provide a way of finding the configuration-defined default value for
       the PATH environment variable. Since PATH can be modified by  the  user
       to include directories that could contain utilities replacing the stan-
       dard utilities, shell scripts need a way to determine  the  system-sup-
       plied  PATH environment variable value that contains the correct search
       path for the standard utilities. It was later suggested that access  to
       the other variables described in this volume of POSIX.1-2008 could also
       be useful to applications.

       This functionality of getconf  would  not  be  adequately  subsumed  by
       another command such as:

	   grep var /etc/conf

       because	such a strategy would provide correct values for neither those
       variables that can vary at runtime, nor those that can  vary  depending
       on the path.

       Early  proposal	versions  of  getconf specified exit status 1 when the
       specified variable was valid, but not defined on the system. The output
       string  "undefined"  is	now used to specify this case with exit code 0
       because so many things depend on an exit code of zero when  an  invoked
       utility is successful.

FUTURE DIRECTIONS
       None.

SEE ALSO
       c99

       The  Base  Definitions  volume  of POSIX.1-2008, Chapter 8, Environment
       Variables, Section 12.2, Utility Syntax Guidelines, <limits.h>

       The System Interfaces volume of POSIX.1-2008,  confstr(),  fpathconf(),
       sysconf(), system()

COPYRIGHT
       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 Electri-
       cal  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.ker-
       nel.org/doc/man-pages/reporting_bugs.html .



IEEE/The Open Group		     2013			   GETCONF(1P)