Github search is fine, do not get me wrong. But this is like telling someone lamenting on the hypothetical end of Google search: "Just use the search function in Facebook, you don't need more"

GitHub's search doesn't support regular expressions.

(I'm aware you can clone the repo and search it locally, but that somewhat defeats the point - especially for large projects.)

My primary use of Google Code search was, searching for this rare function (like a POSIX one) whose man page I can't understand and is largely undocumented elsewhere. I would often try to understand how other projects are using this function via internet-wide code search. :D

While Github is great, I think it still hosts only a small fraction of all the code that is public.

Github is a great alternative for Google Code.

Nothing currently out there is as good as Google Code Search was: http://en.wikipedia.org/wiki/Google_Code_Search

Can you search github with a regex?

We use github enterprise and I've only heard complaints about its search capabilities.