defined(my $pid = fork) or die "Can't fork $!";

# we now have two scripts running in parallel

print "I am the child\n" if $pid == 0;

print "I am the parent\n" if $pid != 0;

# this is another way to determine who we are

if ($pid) {
    # do parent stuff
    print "Do as I say!\n";
}
else {
    # do child stuff
    print "I am not deaf, I'm ignoring you!\n";
}