unless ($args =~ /\-rs(\s+)(\S+)/ && $args =~ /\-p(\s+)(\S+)/ && $args =~ /\-P(\s+)(\S+)/) {
   $args .= " --rs $str";
}

##</code><code>##

if ($args =~ /\-rs(\s+)(\S+)/ || $args =~  /\-p(\s+)(\S+)/ || $args =~  /\-P(\s+)(\S+)/) {
    // do nothing
} else {
    $args .= " --rs $str";
}

##</code><code>##

unless (! $args =~ /\-rs(\s+)(\S+)/ && ! $args =~ /\-p(\s+)(\S+)/ && ! $args =~ /\-P(\s+)(\S+)/) {
   $args .= " --rs $str";
}