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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)
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.
getconf — get configuration values
getconf [−v specification] system_var
getconf [−v specification] path_var pathname
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.
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.
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.
Not used.
None.
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.
Default.
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.
The standard error shall be used only for diagnostic messages.
None.
None.
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.
Default.
The following sections are informative.
None.
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
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.
None.
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)
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)
Pages that refer to this page: poll.h(0p), stddef.h(0p), sys_types.h(0p), termios.h(0p), wchar.h(0p), c99(1p), fpathconf(3p), sysconf(3p)