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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 dif-
       fer (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 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 environment.

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 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 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 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 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 supported:

               * 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 Val-
                 ues''  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, Internationalization Variables for the prece-
              dence 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 exam-
              ple, 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  writ-
              ten 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 conf-
       str() 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 for-
       mat:


              "%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 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 supplies a value that corresponds to the condi-
       tions 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 config-
       uration-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-supplied 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(), pathconf(), sysconf(), system()

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Stan-
       dard  for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifica-
       tions 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 Stan-
       dard, 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)