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GETCONF(P) 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 oper-
ating 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 vari-
ables 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 enclos-
ing 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 con-
fstr() 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, Internationalization Variables for the precedence of interna-
tionalization 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 char-
acters 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
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 exe-
cuted, 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 vari-
able 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(), sys-
tem()
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 original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
POSIX 2003 GETCONF(P)
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