1 .\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
3 .\" Permission is granted to make and distribute verbatim copies of this
4 .\" manual provided the copyright notice and this permission notice are
5 .\" preserved on all copies.
7 .\" Permission is granted to copy and distribute modified versions of this
8 .\" manual under the conditions for verbatim copying, provided that the
9 .\" entire resulting derived work is distributed under the terms of a
10 .\" permission notice identical to this one.
12 .\" Since the Linux kernel and libraries are constantly changing, this
13 .\" manual page may be incorrect or out-of-date. The author(s) assume no
14 .\" responsibility for errors or omissions, or for damages resulting from
15 .\" the use of the information contained herein. The author(s) may not
16 .\" have taken the same level of care in the production of this manual,
17 .\" which is licensed free of charge, as they might when working
20 .\" Formatted or processed versions of this manual, if unaccompanied by
21 .\" the source, must acknowledge the copyright and authors of this work.
23 .\" Modified Sat Jul 24 19:53:02 1993 by Rik Faith (faith@cs.unc.edu)
24 .\" FIXME Many more values for 'name' are supported, some of which
25 .\" are documented under 'info confstr'.
26 .\" See <bits/confname.h> for the rest.
27 .\" These should all be added to this page.
28 .\" See also the POSIX.1-2001 specification of confstr()
29 .TH CONFSTR 3 2010-02-03 "GNU" "Linux Programmer's Manual"
31 confstr \- get configuration dependent string variables
34 .B #include <unistd.h>
36 .BI "size_t confstr(int " "name" ", char *" buf ", size_t " len );
40 Feature Test Macro Requirements for glibc (see
41 .BR feature_test_macros (7)):
45 _POSIX_C_SOURCE\ >=\ 2 || _XOPEN_SOURCE
48 gets the value of configuration-dependent string variables.
52 argument is the system variable to be queried.
53 The following variables are supported:
55 .BR _CS_GNU_LIBC_VERSION " (GNU C library only; since glibc 2.3.2)"
56 A string which identifies the GNU C library version on this system
59 .BR _CS_GNU_LIBPTHREAD_VERSION " (GNU C library only; since glibc 2.3.2)"
60 A string which identifies the POSIX implementation supplied by this
61 C library (e.g, "NPTL 2.3.4" or "linuxthreads-0.10").
66 variable which indicates where all the POSIX.2 standard utilities can
75 copies the value of the string to
79 characters if necessary, with a null byte (\(aq\\0\(aq) as terminator.
80 This can be detected by comparing the return value of
91 just returns the value as defined below.
95 is a valid configuration variable,
97 returns the number of bytes (including the terminating null byte)
98 that would be required to hold the entire value of that variable.
99 This value may be greater than
101 which means that the value in
107 is a valid configuration variable,
108 but that variable does not have a value, then
113 does not correspond to a valid configuration variable,
128 The following code fragment determines the path where to find
129 the POSIX.2 system utilities:
137 n = confstr(_CS_PATH,NULL,(size_t) 0);
141 confstr(_CS_PATH, pathbuf, n);