sub read_new_lines {
        my ($fn, $offset) = @_;
        use IO::File;
        my $fh = new IO::File($fn);
        $fh or die "Failed to read '$fn' ($!)\n";
        seek($fh, $offset, 1) or die "Failed seek ($!)\n";
        chomp(my @lines = <$fh>);
        return (@lines);
    }