Return_Values

   x                  Pointer to a valid group structure containing
                      a matching entry.
   NULL               Indicates an error.

                      Note: The return value points to a static area
                      which is overwritten by subsequent calls to
                      getgrent, getgrgid, or getgrnam.

                      On error, the function sets the return value
                      to one of the following:

                      o  EACCES - The user process does not have
                         appropriate privileges enabled to access
                         the user authorization file.

                      o  EIO - An I/O error has occurred.

                      o  EINTR - A signal was intercepted during
                         getgrnam.

                      o  EMFILE - OPEN_MAX file descriptors are
                         currently open in the calling process.

                      o  ENFILE - The maximum allowable number of
                         files is currently open in the system.

                      Applications wishing to check for error
                      situations should set errno to 0 before
                      calling getgrnam. If errno is set on return,
                      an error occurred.