first-in first-out
     
         fifo, or "queue" a data structure or hardware
        buffer from which items are taken out in the same order they
        were put in.  also known as a "shelf" from the analogy with
        pushing items onto one end of a shelf so that they fall off
        the other.  a fifo is useful for buffering a stream of data
        between a sender and receiver which are not synchronised -
        i.e. not sending and receiving at exactly the same rate.
        obviously if the rates differ by too much in one direction for
        too long then the fifo will become either full blocking the
        sender or empty blocking the receiver.  a unix pipe
        is a common example of a fifo.
     
        a fifo might be but isn't ever? called a lilo - last-in
        last-out.  the opposite of a fifo is a lifo last-in
        first-out or "stack".
     
        1999-12-06
     
     
see also:
block unix pipe stack