CONFSTR
Section: Linux Programmer's Manual (3)
Updated: 2017-09-15
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NAME
confstr - get configuration dependent string variables
SYNOPSIS
#include <unistd.h>
size_t confstr(int name, char *buf, size_t len);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
confstr():
_POSIX_C_SOURCE >= 2 || _XOPEN_SOURCE
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
PATH
variable 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 (aq\0aq) 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.
ERRORS
- EINVAL
-
The value of
name
is invalid.
ATTRIBUTES
For an explanation of the terms used in this section, see
attributes(7).
| Interface | Attribute | Value
|
|
confstr()
| Thread safety | MT-Safe
|
CONFORMING TO
POSIX.1-2001, POSIX.1-2008.
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);
SEE ALSO
getconf(1),
sh(1),
exec(3),
fpathconf(3),
pathconf(3),
sysconf(3),
system(3)
COLOPHON
This page is part of release 4.13 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/.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- ATTRIBUTES
-
- CONFORMING TO
-
- EXAMPLE
-
- SEE ALSO
-
- COLOPHON
-
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- Running on 
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