#!/usr/bin/perl -w

my $hp = 100;
my $pid;

sub get_hit;
sub get_hit {
    unless (-- $hp) {
        kill USR2 => $pid or warn "Failed to send victory: $!\n";
        print "$$: Arrrgh, I am dying!\n";
        exit;
    }
    print "$$: I got hit! $hp hitpoints left.\n";
    $SIG {USR1} = \&get_hit;
}

$SIG {USR1} = \&get_hit;
$SIG {USR2} = sub {print "$$: I won! I won!\n"; exit};

$pid = fork;
die "Fork failed\n" unless defined $pid;
$pid ||= getppid;

while (1) {
    my $timeleft = rand 1;
    (undef, $timeleft) = select (undef, undef, undef, $timeleft)
        while $timeleft;
    kill USR1 => $pid;  #  Ignore errors.
}

__END__