Ask HN: How to search for special characters

As a programmer, I constantly find myself searching for special characters in reference texts. For example, the meaning of "!~" in Ruby and the meaning of "star star" (HN seems to strip out double-* for some reason) in traversing directories. While I found the answers to these questions through experiments of my own, I was wondering if there is a search engine out there that can accommodate searches of special characters.