I'm looking for a distributed solution to do regular expression searches over a large directory structure with many nested directories and files. Ideally it will be also able to search file/directory names, but I only really need it to be able to search file contents. I would like for it to scale automatically as the size of the directory structure increases. It will need to be indexed to be computationally efficient, perhaps using Russ Cox's/Google's indexing method. I need it to support updating the index without completely rebuilding it from scratch. Ex: if I modify one file, it shouldn't have to reindex the entire directory structure. Ideally it would run on Linux and be free. Any filesystem will do.