I am bit surprised by the downvotes. I guess it seems that people seem to be interested in getting a full text search, which for me has never really worked well because results are too noisy (thinking back at least to solutions such as copernic).
Searching within file contents seems to lack good options right now. Historically you had X1 desktop search, Google had a desktop search product, I think copernic. But most seem to be out of date.