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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 (con-
sult 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 envi-
ronment.

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 Inter-
faces 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 Inter-
faces 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, Internationalization Variables for the precedence of international-
ization 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 stan-
dard 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 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 conditions when
the program was either compiled or executed, depending on the implementation; the system() call to getconf always sup-
plies 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-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, Standard for
Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copy-
right (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.open-
group.org/unix/online.html .

IEEE/The Open Group 2003 GETCONF(1P)