sub killchd ($;$) {
    use Proc::ProcessTable;
    my $sig = ($_[1] =~ /^\-?\d+$/) ? $_[1] : 0;
    my $proc = Proc::ProcessTable->new;
    my %fields = map { $_ => 1 } $proc->fields;
    return undef unless exists $fields{'ppid'};
    foreach (@{$proc->table}) {
        kill $sig, $_->pid if ($_->ppid == $_[0]);
    };
    kill $sig, $_[0];
};