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

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

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 operand 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 configuration variables
	      shall be determined. If this option is not specified, the  values  returned  corre-
	      spond 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 commands 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 commands 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 commands of the form:

	      getconf -v POSIX_V6_LP64_OFF64 ...

       determine values for configuration variables corresponding to the POSIX_V6_LP64_OFF64 com-
       pilation 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 commands 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 fpathconf()  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 variables  shall  be  sup-
	      ported:

	       * The  names  in  the  Variable	column	of  the  table	in the DESCRIPTION of the
		 sysconf() function in the  System  Interfaces	volume	of  IEEE Std 1003.1-2001,
		 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 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 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 getconf:

       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.

       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 argu-
	      ments).

       LC_MESSAGES
	      Determine the locale that should be used to affect the format and contents of diag-
	      nostic 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 avail-
       able  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 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 specific directory:

	      getconf NAME_MAX /usr

       The following example shows how to deal more carefully with results that might be unspeci-
       fied:

	      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 supplies a value that cor-
       responds  to the conditions when the program was either compiled or executed, depending on
       the implementation; the system() call to getconf always supplies a value corresponding  to
       conditions 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 standard utilities, shell scripts need a way to  determine  the  system-sup-
       plied  PATH environment variable value that contains the correct search path for the stan-
       dard 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 Inter-
       faces volume of IEEE Std 1003.1-2001, confstr(), pathconf(), 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 orig-
       inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group			       2003				       GETCONF(P)


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