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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)):

       getcwd(): _POSIX_C_SOURCE >= 2 || _XOPEN_SOURCE || _POSIX_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 "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 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

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