CONFSTR(3)

NAME
confstr - get configuration dependent string variables

SYNOPSIS
#define _POSIX_C_SOURCE 2
or
#define _XOPEN_SOURCE
#include <unistd.h>

size_t confstr(int name, char *buf, size_t len);

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 characters if necessary, with a null byte ('\0') 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 does not correspond to a valid configuration variable, confstr() returns 0.

EXAMPLES
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);
if ((pathbuf = malloc(n)) == NULL) abort();
confstr(_CS_PATH, pathbuf, n);

ERRORS
If the value of name is invalid, errno is set to EINVAL.

CONFORMING TO
proposed POSIX.2

BUGS
POSIX.2 is not yet an approved standard; the information in this manpage is subject to change.

SEE ALSO
sh(1), exec(3), system(3)