Ask HN: Full-text search of Unix files?

I have a lot of notes organized as text files in a directory hierarchy on my Unix machine. I would like to index and search these notes, using full-text search and approximate matching (so grep does not suffice). I prefer a command-line utility. I am looking for a simple application that works out-of-the-box, no fuss, no muss, so something like Lucene seems overblown. Any suggestions?