Getting the Most out of ack

Published on Oct. 11, 2013, 11:29 p.m.

ack grep tools

ack is an amazing tool. If you're not familiar with it, it's a lot like grep (the official site is at It's a command-line tool that helps you find things in files, particularly source code. However, like a lot of command-line tools, it's all-too-easy to learn just the basics and forget that many of these tools can do so much more!

Without further ado, here are a few of the ways I frequently use ack while working with Django.

Ignoring folders

It's so frustrating to search for a snippet of python code, only to have your screen fill up with irrelevant results (I'm looking at you migrations and css files!)

When this happens, just ignore the stuff you don't need:

ack --ignore-dir=myapp/migrations

Ingoring files

While we're at it, you can also ignore specific files, or any file that matches a regex. Perhaps you're looking for reference to a Django model, but you don't need to know that it's in, so just ignore that file!

ack SomeModel

Better, but you might also want to ignore that model.js file (or perhaps it's called model_views.js). You can do that with a simple regex! And while we're at it, lets go ahead and ignore any migrations:

ack --ignore-file=match:/^model/ --ignore-dir=migrations/ SomeModel

Just Python, please

ack also lets you restrict searches to specific file types:

ack --type=python SomeModel

There's also a shortcut for this:

ack --python SomeModel

Or ruby if you prefer:

ack --ruby 'def foo'

Similarly, you can tell ack to ignore any files that it doesn't understand with the -k or --known-types flag.

ack -k SomeCode

To get a list of all the filetypes that ack knows about, just run:

ack --help-types

Be insensitive!

For some reason, I sometimes forget that default searches are case sensitive. If, like me, you're pronE tO TYpos, you can perform case insensitive searches with:

ack -i whatever

Digging deeper

As you might have noticed, ack comes with some default behavior. You can inspect these defaults with:

ack --dump

Now, if you want to start customizing this behavior, create an .ackrc file, and tweak it to your heart's content. A good way to get started is to let ack generate this file for you! (careful! this command will overwrite your .ackrc file if you already have one.)

ack --create-ackrc > ~/.ackrc

Have some fun

The ack developers are not without a sense of humor. Certainly you should take the time to investigate all of the following:

ack --bar
ack --cathy
ack --thpppt

Wrapping Up

There's so much more to ack than what I've listed here. Do yourself a favor and periodically skim the output of ack --help, then take some time to look through the manpage (man ack).

Happing searching!

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