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

       confstr - get configuration dependent string variables

       #include <unistd.h>

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

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       getcwd(): _POSIX_C_SOURCE >= 2 || _XOPEN_SOURCE || _POSIX_SOURCE

       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

              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.

       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.

       EINVAL If the value of name is invalid.


       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)
           confstr(_CS_PATH, pathbuf, n);

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

       This page is part of release 3.22 of the Linux man-pages project.  A description of the project,  and  informa-
       tion about reporting bugs, can be found at

GNU                               2008-08-29                        CONFSTR(3)