find/replace multiple line breaks (paragraph breaks) into 1

https://productforums.google.com/forum/#!topic/docs/LJwSVUBoJi4

Well, after playing around a bit, I discovered a solution on my own. Go to find/replace, check off regular expressions, and enter the following in the find field:

\n+(?=\n)

Leave the replace field blank. This will match any number of breaks that are followed by an additional break, but it will NOT include the final break, therefore will not replace it, but instead will just leave it. In case anyone is interested, in the world of regular expressions, this is called a positive lookahead.

https://productforums.google.com/forum/#!msg/docs/uTsVxJQ5QkU/eKpVA5gpoT8J