Top 10 reasons to use ack instead of grep. 

• It's blazingly fast because it only searches the stuff you want searched.

• ack is pure Perl, so it runs on Windows just fine.

• The standalone version uses no non-standard modules, so you can put it in your ~/bin without fear.

• Searches recursively through directories by default, while ignoring .svn, CVS and other VCS directories.

• ack ignores most of the crap you don't want to search

• Ignoring .svn directories means that ack is faster than grep for searching through trees.

• Lets you specify file types to search, as in --perl or --nohtml.

• File-filtering capabilities usable without searching with ack -f. This lets you create lists of files of a given type.

• Color highlighting of search results.

• Uses real Perl regular expressions, not a GNU subset.

• Allows you to specify output using Perl's special variables

• Many command-line switches are the same as in GNU grep

• Command name is 25% fewer characters to type! Save days of free-time! Heck, it's 50% shorter compared to grep -r.