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.