lib/SysVIPC.rb
def rcv(type, size, flags = 0)
      res, mtype, mtext = msgrcv(@msgid, size, type, flags)
      check_result(res)
      mtext
    end
def rcv(type, size, flags = 0)
      res, mtype, mtext = msgrcv(@msgid, size, type, flags)
      check_result(res)
      mtext
    end
Receive a message of type +type+, limited to +len+ bytes or fewer.
 See msgrcv(2).