grep is a handy tool and I use it every day. But sometimes I wish it had some more features. For instance full featured Perl compatible regular expressions (PCRE) since the current implementation is not complete and I think it will never be, automatic recursive search, exclusion of non-text files etc.
Here a tool called ack comes into play. It's a search tool and grep replacement written in Perl, which is able to do all these things. Guess what!
grep is probably one of the best known, or let's better say: the most used command line tools on UNIX systems. But not many people know that it is so much more than just a very simple text search command.