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 (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 op-
erand 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 environ-
ment.
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 configu-
ration 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 com-
mands 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 com-
mands 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 com-
mands 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 com-
mands 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 fpath-
conf() 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 vari-
ables shall be supported:
* The names in the Variable column of the table in the DESCRIP-
TION of the sysconf() function in the System Interfaces vol-
ume of IEEE Std 1003.1-2001, except for the entries corre-
sponding 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 under-
score. 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 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 under-
score. 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 get-
conf:
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 Vari-
ables 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
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 cur-
rent 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 spe-
cific 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 sup-
plies a value that corresponds to the conditions when the program was
either compiled or executed, depending on the implementation; the sys-
tem() call to getconf always supplies a value corresponding to condi-
tions 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 stan-
dard utilities, shell scripts need a way to determine the system-sup-
plied 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(), path-
conf(), 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, 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 .
IEEE/The Open Group 2003 GETCONF(1P)
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