ack is the replacement I wrote for grep, aimed at large trees of heterogeneous code.

Using it will change your life, but why? Here's my top 10 list:

1. Searches recursively through directories by default, while ignoring .svn, CVS and other VCS directories.
   • Which would you rather type?
     $ grep pattern $(find . | grep -v .svn)
     $ ack pattern
2. ack ignores most of the crap you don't want to search
   • VCS directories
   • blib, the Perl build directory
   • backup files like foo~
   • binary files
3. Lets you specify file types to search, as in --perl or --nohtml.
   • Which would you rather type?
     $ grep pattern $(find . -name '*.pl' -or -name '*.pm' -or -name '*.pod' | grep -v .svn)
     $ ack --perl pattern
   Note that ack's --perl also checks the shebang lines of files without suffixes, which the find command will not.
4. File-filtering capabilities usable without searching with ack -f. Want a list of all Perl files in a tree? Use ack -f --perl.
5. Color highlighting of search results.
6. Uses real Perl regular expressions, not a GNU subset.
7. Allows you to specify output using Perl's special variables
   • Example: ack '(Mr|Mr?s). (Smith|Jones)' --output='$&'
8. Many command-line switches are the same as in GNU grep:
   -w does word-only searching
   -c shows counts per file of matches
   -l gives the filename instead of matching lines
   etc.
9. ack is pure Perl, so consistent across all platforms.
10. Command name is 25% shorter. :-) Heck, it's 50% shorter compared to grep -r.

To install it, install the Perl module App::Ack. Your coding life will never be the same.

Visit the home page at http://petdance.com/ack