How do I search strings in redis?

You need to set up an index using sets or sorted sets that you write to when you save anything.

There's a good writeup at http://web.archive.org/web/20121013063245/http://playnice.ly/blog/2010/05/05/a-fast-fuzzy-full-text-index-using-redis that is pretty close to what I use myself.

In Redis, there is no way to search the value of a key. The only way you can "find" a string, is via the keys command. The only downside is that it searches the key names, not the value. The way you can get around this is by having your search string as the key and then have the value of said key your ID. I use an autocompleate function on my side, and I use another database that just contains search strings with have an ID as a value.