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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  IEEE Std 1003.1-2001  or  by  the	System
       Interfaces  volume  of IEEE Std 1003.1-2001 (see the OPERANDS section).
       The value shall reflect conditions in the  current  operating  environ‐
       ment.

OPTIONS
       The  getconf  utility  shall  conform to the Base Definitions volume of
       IEEE Std 1003.1-2001, Section 12.2, Utility Syntax Guidelines.

       The following option shall be supported:

       -v  specification

	      Indicate a specific specification and version for which configu‐
	      ration  variables	 shall	be  determined.	 If this option is not
	      specified, the values returned correspond to  an	implementation
	      default conforming compilation environment.

       If the command:

	      getconf _POSIX_V6_ILP32_OFF32

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

	      getconf -v POSIX_V6_ILP32_OFF32 ...

       determine values	 for  configuration  variables	corresponding  to  the
       POSIX_V6_ILP32_OFF32  compilation  environment  specified  in  c99, the
       EXTENDED DESCRIPTION.

       If the command:

	      getconf _POSIX_V6_ILP32_OFFBIG

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

	      getconf -v POSIX_V6_ILP32_OFFBIG ...

       determine  values  for  configuration  variables	 corresponding	to the
       POSIX_V6_ILP32_OFFBIG compilation environment  specified	 in  c99,  the
       EXTENDED DESCRIPTION.

       If the command:

	      getconf _POSIX_V6_LP64_OFF64

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

	      getconf -v POSIX_V6_LP64_OFF64 ...

       determine values	 for  configuration  variables	corresponding  to  the
       POSIX_V6_LP64_OFF64  compilation	 environment  specified	 in  c99,  the
       EXTENDED DESCRIPTION.

       If the command:

	      getconf _POSIX_V6_LPBIG_OFFBIG

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

	      getconf -v POSIX_V6_LPBIG_OFFBIG ...

       determine  values  for  configuration  variables	 corresponding	to the
       POSIX_V6_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	fpath‐
	      conf()  function	defined	 in  the  System  Interfaces volume of
	      IEEE Std 1003.1-2001, without the	 enclosing  braces,  shall  be
	      supported.  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	 vari‐
	      ables shall be supported:

	       * The names in the Variable column of the table in the DESCRIP‐
		 TION of the sysconf() function in the System Interfaces  vol‐
		 ume  of  IEEE Std 1003.1-2001,	 except for the entries corre‐
		 sponding   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 under‐
	      score.  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 Interfaces volume  of
		 IEEE Std 1003.1-2001, 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 Definitions volume of
		 IEEE Std 1003.1-2001, 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 under‐
	      score.  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 variables
	      that are unset or null. (See  the	 Base  Definitions  volume  of
	      IEEE Std 1003.1-2001,  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 IEEE Std 1003.1-2001, 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  cur‐
	      rent 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 infinite.
		  else
		      echo PATH_MAX in /usr is $value.
		  fi
	      else
		  echo Error in getconf.
	      fi

       Note that:

	      sysconf(_SC_POSIX_C_BIND);

       and:

	      system("getconf POSIX2_C_BIND");

       in  a  C	 program could give different answers. The sysconf() call sup‐
       plies a value that corresponds to the conditions when the  program  was
       either  compiled or executed, depending on the implementation; the sys‐
       tem() call to getconf always supplies a value corresponding  to	condi‐
       tions when the program is executed.

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  IEEE Std 1003.1-2001
       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  IEEE Std 1003.1-2001,  <limits.h>,
       the  System Interfaces volume of IEEE Std 1003.1-2001, confstr(), path‐
       conf(), sysconf(), system()

COPYRIGHT
       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 original Standard can be obtained online
       at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group		     2003			   GETCONF(1P)
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