Question:

I want to match regexes (at least the basic ones, not all their possible kinds... for now...) in a text of Ruby script.<br /> It's something like a... \/\^? oh my god... \$?\/[eimnosux]*

Maybe I need recursive regex here.

As I commented above, you'll need to parse Ruby to differentiate division slashes and regex delimiters. But for the simplest, SIMPLEST case without worrying about this, how about:

regex_match = %r{/(?:[^/\\]|\\.)+/[mgixo]*}

That is "A forward slash, followed by one or more things that either aren't a forward slash or a backslash, or are a backslash followed by something else, finally followed by a slash, and possibly some regex flags."