Return_Values

   0                  Successful completion.
   x                  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
                         getgrgid.

                      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.

                      o  ERANGE - Insufficient storage was supplied
                         through the buffer and bufsize arguments
                         to contain the data to be referenced by the
                         resulting group structure.