ack 2.0 is a text searching utility optimized for searching trees of source code.

Incompatibilities with ack 1.x

ack 2 makes some big changes in its behaviors that could trip up users who are used to the idiosyncracies of ack 1.x. These changes could affect your searching happiness, so please read them.

• ack's default behavior is now to search all files that it identifies as being text. ack 1.x would only search files that were of a file type that it recognized.

• Removed the -a and -u options since the default is to search all text files.

• Removed the --binary option. ack 2.0 will not find and search through binary files.

• Removed the --skipped option.

• Removed the --invert-file-match option. -v now works with -g.

  List files that do not match /foo/

  ack -g foo -v

• -g now obeys all regex options: -i, -w, -Q, -v

• Removed the -G switch, because it was too confusing to have two regexes specified on the command line. Now you use the -x switch to pipe filenames from one ack invocation into another.

  Search files with filename matching "sales" for the string "foo"

  ack -g sales | ack -x foo

List files that do not match /foo/

Search files with filename matching "sales" for the string "foo"

New features in ack 2.0

ack 2.0 will:

• by default search all text files, as identified by Perl's -T operator

  • We will no longer have a -a switch.

• improved flexibility in defining filetype selectors

  • name equality ($filename eq 'Makefile')
  • glob-style matching (*.pl identifies a Perl file)
  • regex-style matching (/\.pl$/i identifies a Perl file)
  • shebang-line matching (shebang line matching /usr/bin/perl/ identifies a Perl file)

• support for multiple ackrc files

  • global ackrc (/etc/ackrc)
    • https://github.com/petdance/ack/issues/#issue/79
  • user-specific ackrc (~/.ackrc)
  • per-project ackrc files (~/myproject/ackrc)

• you can use --dump to figure which options are set where

• all inclusion/exclusion rules will be in the ackrc files

  • ack 2.0 has a set of definitions for filetypes, directories to include or exclude, etc, but these are only included so you don't need to ship an ackrc file to a new machine. You may tell ack to disregard these defaults if you like.