ack

Search for a pattern in current directory recursively

$ ack [pattern]

$ ack --type=[perl|python|ruby|js] [pattern]

$ ack -i [pattern]

$ ack -l [pattern]

$ ack -C [3] [pattern]

ack [options] pattern [file|directory...]

ack is a code-searching tool designed as an alternative to grep, optimized for programmers. It automatically skips backup files, version control directories (.git, .svn), and binary files while searching recursively through source code.
The tool provides built-in file type filtering, allowing searches limited to specific programming languages. Output is formatted with color highlighting and file grouping for easier reading. It uses Perl regular expressions, providing powerful pattern matching capabilities.

-i, --ignore-case

Case insensitive search

Invert the match; select non-matching lines

Match whole words only

Print only filenames containing matches

Print filenames that don't contain matches

Print count of matching lines per file

Print num lines of context around matches

Print num lines after each match

Print num lines before each match

Search only files of TYPE (perl, python, ruby, js, etc.)

Disable color output

Print files that would be searched (dry run)

Ignore directory name

List all recognized file types

ack is slower than newer tools like ripgrep or ag (The Silver Searcher) on large codebases. It requires Perl to be installed. Some file types may not be recognized by default and require custom configuration in .ackrc.

ack was created by Andy Lester and first released in 2005. It was designed to be a better grep for programmers, addressing common frustrations with searching through codebases. The tool influenced later search tools like ag and ripgrep.

grep(1), ag(1), rg(1), git-grep(1)