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 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 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.
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);