Emacs: incremental search with rgrep and lgrep

Question

Is there an rgrep and lgrep version of incremental search?

Answer 1

I don't know what lgrep is, but I've used these notes for Emacs search (and replace) through the file system:

http://xahlee.org/emacs/find_replace_inter.html

Answer 2

Do you mean and incremental regex search? If so M-x isearch-forward-regexp will do it.