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 sup‐
       ported:

       _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 utili‐
              ties 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 (includ‐
       ing 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 trun‐
       cated.

       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, conf‐
       str() returns 0, and errno is set to EINVAL.

ERRORS
       EINVAL 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  utili‐
       ties:

           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) sysconf(3) pathconf(3) system(3)

COLOPHON
       This  page  is  part of release 3.74 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 http://www.kernel.org/doc/man-pages/.



GNU                                         2014-03-20                                 CONFSTR(3)