ack

A text search tool that is better than grep.

Installation

# On Ubuntu, install ack-grep, as the name 'ack' is taken by other software in Debian-based systems.
sudo apt-get install ack-grep

# On Alpine Linux using the apk package manager:
apk add ack

Options

These parameters are highly used in Linux, especially if you use Vim as an IDE.

-c (count) / -i (ignore case) / -h (no filename) /
-l (filenames only) / -n (line number) / -v (invert match)

Features

The official ack website lists five main selling points for this tool:

1. Very fast: It only searches what's meaningful.
2. User-friendly search: It ignores things that are not your source code.
3. Designed for source code search: Accomplish tasks with fewer keystrokes.
4. Highly portable: Very lightweight and easy to port.
5. Free and Open Source.

Examples

The usage can be roughly categorized into:

Searching
Search output
File presentation
File finding
File inclusion/exclusion

Common grep operations:

grep -r 'hello_world' # Simple recursive search
grep '^hello_world' . # Simple regex
ls -l | grep .py      # Pipe usage

Searching

Simple text search, recursive by default.

ack-grep hello
ack-grep -i hello
ack-grep -v hello
ack-grep -w hello
ack-grep -Q 'hello*'

Search Output

Processing search results, such as showing only filenames.

ack-grep --line=1       # Output the first line of all files
ack-grep -l 'hello'     # Filenames that contain the match
ack-grep -L 'print'     # Filenames that do NOT contain the match

File Presentation

How the output is displayed. You can practice with these parameters:

ack-grep hello --pager='less -R'    # Display using less
ack-grep hello --noheading          # Do not show filename headers
ack-grep hello --nocolor            # Do not color match strings

File Finding

Yes, it can find files, saving you the trouble of combining find and grep, even though the Linux philosophy is "one tool for one task."

ack-grep -f hello.py                # Find files matching the exact name
ack-grep -g hello.py$               # Find files matching a regex
ack-grep -g hello --sort-files      # Find and then sort results

File Inclusion/Exclusion

File filtering is a very useful feature. If you've ever accidentally hit a keyword in a log file while searching project source code, you'll find this helpful.

ack-grep --python hello             # Search only in Python files
ack-grep -G hello.py$ hello         # Search only in files matching the regex

References

• Official ack Website