Section (3) confstr
Name
confstr — get configuration dependent string variables
Synopsis
#include <unistd.h>
size_t
confstr( |
int name, |
| char *buf, | |
size_t len); |
![[Note]](../stylesheet/note.png) |
Note | ||
|---|---|---|---|
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DESCRIPTION
confstr() gets the value of
configuration-dependent string variables.
The name argument
is the system variable to be queried. The following variables
are supported:
_CS_GNU_LIBC_VERSION(GNU C library only; since glibc 2.3.2)-
A string which identifies the GNU C library version on this system (e.g., glibc 2.3.4).
_CS_GNU_LIBPTHREAD_VERSION(GNU C library only; since glibc 2.3.2)-
A string which identifies the POSIX implementation supplied by this C library (e.g., NPTL 2.3.4 or linuxthreads-0.10).
_CS_PATH-
A value for the
PATHvariable which indicates where all the POSIX.2 standard utilities can be found.
If buf is not NULL
and len is not zero,
confstr() copies the value of
the string to buf
truncated to len −
1 bytes if necessary, with a null byte (_zsingle_quotesz_ _zsingle_quotesz_) as
terminator. This can be detected by comparing the return
value of confstr() against
len.
If len is zero and
buf is NULL,
confstr() just returns the
value as defined below.
RETURN VALUE
If name is a valid
configuration variable, confstr() returns the number of bytes
(including the terminating null byte) that would be required
to hold the entire value of that variable. This value may be
greater than len,
which means that the value in buf is truncated.
If name is a valid
configuration variable, but that variable does not have a
value, then confstr() returns
0. If name does not
correspond to a valid configuration variable, confstr() returns 0, and errno is set to EINVAL.
ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).
| Interface | Attribute | Value |
confstr() |
Thread safety | MT-Safe |
EXAMPLE
The following code fragment determines the path where to find the POSIX.2 system utilities:
char *pathbuf; size_t n; n = confstr(_CS_PATH, NULL, (size_t) 0); pathbuf = malloc(n); if (pathbuf == NULL) abort(); confstr(_CS_PATH, pathbuf, n);
COLOPHON
This page is part of release 5.04 of the Linux man-pages project. A
description of the project, information about reporting bugs,
and the latest version of this page, can be found at
https://www.kernel.org/doc/man−pages/.
|
Copyright (c) 1993 by Thomas Koenig (ig25rz.uni-karlsruhe.de) %%%LICENSE_START(VERBATIM) Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Since the Linux kernel and libraries are constantly changing, this manual page may be incorrect or out-of-date. The author(s) assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein. The author(s) may not have taken the same level of care in the production of this manual, which is licensed free of charge, as they might when working professionally. Formatted or processed versions of this manual, if unaccompanied by the source, must acknowledge the copyright and authors of this work. %%%LICENSE_END Modified Sat Jul 24 19:53:02 1993 by Rik Faith (faithcs.unc.edu) FIXME Many more values for _zsingle_quotesz_name_zsingle_quotesz_ are supported, some of which are documented under _zsingle_quotesz_info confstr_zsingle_quotesz_. See <bits/confname.h> for the rest. These should all be added to this page. See also the POSIX.1-2001 specification of confstr() |