sub pipe_to_fork {
    my $parent = shift;
    pipe my $child, $parent or die;
    my $pid = fork();
    die "fork() failed: $!" unless defined $pid;
    if ($pid) {
        close $child;
    }
    else {
        close $parent;
        open(STDIN, "<&=" . fileno($child)) or die;
    }
    $pid;
}