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CONFSTR(3)                 Linux Programmer's Manual                CONFSTR(3)

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 sys-
              tem (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  ('\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.
ERRORS
       EINVAL If the value of name is invalid.
CONFORMING TO
       POSIX.1-2001.
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
       sh(1), exec(3), system(3)
COLOPHON
       This page is part of release 3.53 of the Linux  man-pages  project.   A
       description  of  the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.

GNU                               2012-05-10                        CONFSTR(3)