One of my senior brother just asked me, how to add no follow rel for comments in wordpress. May be there is plugin for this. Look to my code
How to use:
1.Open the functions.php file in ur current theme and put these code within php tags.

What it will do:
1. Will add ‘no follow’ as rel in url , if comment contains any url.
2. Will ad ‘external’ as rel in url , if comment contains any url.
3. Will add target=”_blank” in comment author’s url so that their web url open’s in new window/new tab as in browser settings
4. Will add target=”_blank” to url, if comment contains any url
5. Wp adds ‘no follow’, ‘external’ rel in comment author’s url by default. So we don’t need to add this

Tips:
1.If possible upgrade to wp2.8.2

      function nofollow($text) {
	        $text = preg_replace('/<a /i','<a rel="nofollow external" ',$text);
	        $text = preg_replace('/<a /i','<a target="_blank" ',$text);
	        return $text;
    }
    function targetblank($text){
    		$text = preg_replace('/<a /i','<a target="_blank" ',$text);
	        return $text;
    }

    add_filter('comment_text', 'nofollow');
    add_filter('get_comment_author_link','targetblank');

any question ask me
p.s.: post image is just for fun

BTW, are you afraid of editing your functions.php ? Ok, no problem you can add the above piece of code using the bellow wp plugin.

  Wp nofollow plugin for comment (997 bytes, 995 hits)

Duh, you are totally unhappy with this post, na ? You can to treat your commentors with “cake and cook”, ok no problem.Just forget my post and read this blog post …“The Single, Most Profound Way To Thank Your Commenters”.
Happy now ?

Last Update on January 18th, 2010