use strict;
use IO::Pipe;
use IO::Select;

my $pipe = new IO::Pipe;

if ( fork() ) {
    print "Parent live\n";
    $pipe->reader();
    my $ios = IO::Select->new();
    $ios->add($pipe);
    while (1) {
        print "Handles: "
          . scalar $ios->handles . ", "
          . scalar $ios->can_read(1)
          . " ready.\n";
        if ( $ios->can_read(1) ) {
            while (<$pipe>) {
                syswrite( STDOUT, "[r]", 3 );
                print "[d:$_:d]\n";
            }
        }
        else {
            syswrite( STDOUT, "[b]", 3 );
            sleep 1;
        }
    }
}
else {
    print "Child live\n";
    $pipe->writer();
    $pipe->autoflush(1);

    while (1) {
        $pipe->print("HELLO!\n");
        syswrite( STDOUT, "[W]", 3 );
        sleep 1;
    }
}