This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface

Application Usage

       None.

Asynchronous Events

       Default.

Consequences Of Errors

       Default.

       Thefollowingsectionsareinformative.

Copyright

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group  Base
       Specifications  Issue  7, 2018 Edition, Copyright (C) 2018 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 .

       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.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                                   2017                                       GETCONF(1POSIX)

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  POSIX.1‐2017  or  by  the  System
       Interfaces  volume  of POSIX.1‐2017 (see the OPERANDS section). The value shall reflect conditions in the
       current operating environment.

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 POSIX.1‐2017, Section8.2, InternationalizationVariables  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.

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 indeterminate.
               else
                   echo PATH_MAX in /usr is $value.
               fi
           else
               echo Error in getconf.
           fi

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.

Extended Description

       None.

Future Directions

       None.

Input Files

       None.

Name

       getconf — get configuration values

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.1‐2017, 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 POSIX.1‐2017, 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 POSIX.1‐2017, 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 POSIX.1‐2017, 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.

Options

       The getconf utility shall conform to the Base Definitions volume of POSIX.1‐2017, Section12.2,  UtilitySyntaxGuidelines.

       The following option shall be supported:

       -vspecification
                 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_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.

Output Files

       None.

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.

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-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 POSIX.1‐2017 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.

Stderr

       The standard error shall be used only for diagnostic messages.

Stdin

       Not used.

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.1‐2017, 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.

Synopsis

       getconf [-v specification]system_var

       getconf [-v specification]path_varpathname