Thursday, May 26, 2016

Ack, ag... not grep

Grep is a great tool and anyone using any *nix system uses it all the time. In fact you could also use it with Cygwin on Windows. But recently at work, a colleague pointed out that ack and ag are great, much faster tools with better defaults than grep. So while I still go to grep once in a while, ack/ag is my search tool of choice now when doing code-reviews. You can find ack here and ag here. ag is very similar to ack, just even faster (Disclaimer: Only tried this once on my last gig)

While the man page is always a good option, here are some of my favorite switches to get you started.

--java or --ruby: Will limit the search to just files of that type. Meaning it'll ignore a lot of libraries, documentation and other large stuff that happens to be in the same directory

-G cpp$: Search only in files ending with cpp. This one's nice coz if you do --cpp it will search cpp and .h, but you don't want to search inside header files.

--ignore=*.h: Search everywhere except .h files

Recursion: Its on by default, which is almost always what you want in a code-review.

--ignore-dir: Its common to find 567 hits of a function in a source-code-tree and realize that 560 were in a directory 'abc' that you didn't want to search at all. You can use this switch to completely ignore that directory.

--ignore-file: Same as above but for a file. If you have a file in 100 different directories that's matching, but you want to ignore, use this.

-l: This one's similar to grep I think, if you don't want "what" was matched, but where it matched it. Just lists which files matched a pattern.

-i: Same as grep. Case insensitive

-v: Invert match. Same as grep. Case insensitive

The responses for ack were nicer too and more intuitive, I thought. Some of my favorite things:

- Listed filename only once and then all the matches under a file. Grep prints the filename_per _match
- Breaks between files by default. Grep dumps them all together.
- The colors of the response were nicer (IMO)

Also lastly, it appears to have the option to use a .ackrc file to set your options. So then you can just type ack and all the options you set in .ackrc will get picked up on their own.

I mean, you can probably do all this with grep as well, so it isn't meant to say.. 'hey no more grepping for me' .. just that it is a really nice tool that can help in some situations.

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