Regular Expression Wordpress redirection plugin

Question

I'm using the Redirection plugin to Wordpress, but can't get this regex to work. I'm not an expert on regex at all, so I guess I'm doing something wrong.

/(.*)/(.*)/?rel=old
/$1/$2/?rel=new

When doing this I end up with: http://domain.se/something/somestuff/?/?rel=new

It should be: http://domain.se/something/somestuff/?rel=new

Why is it not working and what is that extra /?/

Answer 1

Looks like you forgot to escape the ?.

/(.*)/(.*)/\?rel=old
/$1/$2/?rel=new

In regex, ? means match the preceding character/group zero or one times - so your original regex was looking for an optional / character immediately before rel=old. Of course it didn't find this, and so instead the text matched by the second capture group expanded to encompass the /? characters before rel=old.