How to redirect by adding something after pathauto url? I am trying to do a simple thing.
Whenever an anonymous user views a content , I want to redirect the user to 

node's-url/#overlay=signup

So, how do I modify the URL to use #overlay=signup at the end for anon users?

I tried to do so by implementing rules.
Event: Content is viewed
Condition: User role is anonymous
Action: Redirect url.  

I don't know how to add the pathauto-url/#overlay=signup.
What's what Splash module does. See Thickbox option. More about the module:


  Display any internal path, external URL or text as a splash page before going to the actual frontpage.