I am using few banner exchange and some text exchange services in my site also some text I want to make it in general that has no-follow for all links in my site how i can do it ?
No links in the page containing the code i posted will be followed. However if you make a google (XML) site map or link the pages from other indexed websites they will be indexed. If you don't want the pages to be indexed then use <meta name="robots" content="noindex,nofollow">
No i want my pages to be indexed, I mean outside links other then domains, some sites have this features that's anyone post a link they can but have no follow but all links from domain is follow, like craglist
If you want to allow SEs to follow internal links but not external ones you need to specify which ones should not be followed in the link code. Don't put anything in the head so all the links are followed, then in the ones you don't want to be followed add rel="nofollow" like this: <a href="http://www.externalwebsite.com/" rel="nofollow">External Site</a>
In that case you'll need to use regular expressions to add it to user-supplied links. I recommend breaking the links down completely and re-building them from scratch, in order to better avoid XSS and other nefarious attacks on your users and admins.
Is there is a way to make links no follow in general by using this : but choosing the links that follow by manual ? or its not correct method ?
duperhost, this code: refers to all the links in the page. Google help If after that you put rel="follow" in individual links it will not work as there is no such thing as rel="follow". I guess you want to use rel="follow" because you have control over your internal links and can apply that property to every link, but can't apply rel="nofollow" to external links because they are posted by users. If that's the case you will need to modify your script so that it will include rel="nofollow" in user posted links...