Returns an absolute pathname from the POSIX root.

    Format

      #include  <stdlib.h>

      char realpath  (const char *restrict file_name, char *restrict
                     resolved_name);

1 - Arguments

 file_name

    Pointer to the text string representing the name of the file for
    which you want the absolute path.

 resolved name

    Pointer to the generated absolute path stored as a null-
    terminated string.

2 - Description

    The realpath function returns an absolute pathname from the
    POSIX root. The generated pathname is stored as a null-terminated
    string, up to a maximum of PATH_MAX bytes, in the buffer pointed
    to by resolved_name.

    The realpath function is supported only in POSIX-compliant modes
    (that is, with DECC$POSIX_COMPLIANT_PATHNAMES defined to one of
    the allowed values).

    See also symlink, unlink, readlink, lchown, and lstat.

3 - Return Values

    x                  Upon successful completion, a pointer to the
                       resolved_name.
    NULL               Indicates an error. A null pointer is
                       returned, the contents of the buffer pointed
                       to by resolved_name are undefined, and errno
                       is set to indicate the error:

                       o  ENAMETOOLONG - The length of the file_name
                          argument exceeds PATH_MAX, or a pathname
                          component is longer than NAME_MAX.

                       o  ENOENT - A component of file_name does not
                          name an existing file, or file_name points
                          to an empty string.

                       o  Any errno value from chdir or stat.