PROLOG | NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | STDIN | INPUT FILES | ENVIRONMENT VARIABLES | ASYNCHRONOUS EVENTS | STDOUT | STDERR | OUTPUT FILES | EXTENDED DESCRIPTION | EXIT STATUS | CONSEQUENCES OF ERRORS | APPLICATION USAGE | EXAMPLES | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

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

PROLOG         top

       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         top

       getconf — get configuration values

SYNOPSIS         top

       getconf [−v specification] system_var

       getconf [−v specification] path_var pathname

DESCRIPTION         top

       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.1‐2008 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         top

       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
                 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(1p), 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(1p), 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(1p), 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(1p), the EXTENDED DESCRIPTION.

OPERANDS         top

       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 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.1‐2008, 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
                     Interfaces 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
                     Definitions 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         top

       Not used.

INPUT FILES         top

       None.

ENVIRONMENT VARIABLES         top

       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.1‐2008, Section 8.2, Internationalization
                 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 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         top

       Default.

STDOUT         top

       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         top

       The standard error shall be used only for diagnostic messages.

OUTPUT FILES         top

       None.

EXTENDED DESCRIPTION         top

       None.

EXIT STATUS         top

       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         top

       Default.

       The following sections are informative.

APPLICATION USAGE         top

       None.

EXAMPLES         top

       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

RATIONALE         top

       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.1‐2008 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         top

       None.

SEE ALSO         top

       c99(1p)

       The Base Definitions volume of POSIX.1‐2008, Chapter 8, Environment
       Variables, Section 12.2, Utility Syntax Guidelines, limits.h(0p)

       The System Interfaces volume of POSIX.1‐2008, confstr(3p),
       fpathconf(3p), sysconf(3p), system(3p)

COPYRIGHT         top

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

IEEE/The Open Group                 2013                         GETCONF(1P)