ack

Additional Notes

ack is a grep-like search tool designed for source code. It skips many irrelevant directories and files by default, such as version-control metadata, and offers convenient file-type filtering.

Use ack when searching codebases interactively. For maximum speed in large projects, tools such as rg or ag are also common.

Syntax

ack [options] pattern [path...]

Parameters

• pattern: Text or regular expression to search for.
• path: File or directory to search. Defaults to the current directory.
• options: Matching, output, and file-type filters.

Common Options

• -i: Case-insensitive search.
• -w: Match whole words.
• -l: Show only filenames with matches.
• -L: Show only filenames without matches.
• -n: Do not recurse into subdirectories.
• --type=TYPE: Search only files of a known type.
• --ignore-dir=DIR: Ignore a directory.

Examples

ack "TODO"

Search recursively from the current directory.

ack -i "error" ./src

Search case-insensitively under src.

ack --type=js "fetch"

Search only JavaScript files when the file type is recognized.

ack -l "main"

Print only filenames that contain matches.

Practical Notes

• ack is optimized for human code search, not POSIX portability.
• Use quotes around patterns that contain shell metacharacters.
• If ack is not installed, try grep -R, rg, or ag.