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!
The UNIX philosophy is based on the DRY principle which declares: “Don't repeat yourself”. Therefore, a program just does what it's made for and uses libraries or even other programs on your system to do a more advanced job. Some of these auxiliary programs are user definable and probably you already know the EDITOR environment variable, which specifies your default editor for the console. This is used, e.g., for the command visudo, which opens your /etc/sudoers file safely, or by svn to input a commit comment. But another important component is your console pager, which is used to display textual content on the console.
