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 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 "linux-
              threads-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 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 3.25 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                                                        2010-02-03                                                 CONFSTR(3)