def ipc_set(semid_ds)
      unless Semid_ds === semid_ds
	raise ArgumentError,
	  "argument to ipc_set must be a Semid_ds"
      end
      check_result(semctl(@semid, 0, IPC_SET, semid_ds))
    end
def ipc_set(semid_ds)
      unless Semid_ds === semid_ds
	raise ArgumentError,
	  "argument to ipc_set must be a Semid_ds"
      end
      check_result(semctl(@semid, 0, IPC_SET, semid_ds))
    end
Set the Semid_ds object. See semctl(2).