I would like to know what hook should I used when the permalink/url of a post is modified. My goal is to get the old permalink and new permalink so I can used it for my plugin. Thanks.
[EDIT] Just want to clarify the question. I would like to get the old and new url in a scenario for example, when a user select one its post in the admin area, and edit the current permalink/url(/helloworld) into a new permalink/url(/helloworld_new) of the selected post. I would like to get the complete url the post being edited.