Hi,
I had tried the following example, but it look that the program is not completed (runs in infinite loop?!!) Any idea ? or other example that i can use for running a program that every time any other program tries to read/write from that file the reading/writing program will block until the first will complete ?

    chdir; # go home
    $FIFO = '.signature';
    $ENV{PATH} .= ":/etc:/usr/games";


    while (1) {
        unless (-p $FIFO) {
            unlink $FIFO;
            system('mknod', $FIFO, 'p')
                && die "can't mknod $FIFO: $!";
        }


        # next line blocks until there's a reader
        open (FIFO, "> $FIFO") || die "can't write $FIFO: $!";
        print FIFO "John Smith (smith\@host.org\n";
        close FIFO;
        sleep 2;    # to avoid dup signals
    }
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