ack misses results (vs. grep)

ack is peculiar in that it doesn’t have a blacklist of file types to ignore, but rather a whitelist of file types that it will search in.

To quote from the man page:

With no file selections, ack-grep only searches files of types that it recognizes. If you have a file called foo.wango, and ack-grep doesn’t know what a .wango file is, ack-grep won’t search it.

(Note that I’m using Ubuntu where the binary is called ack-grep due to a naming conflict)

ack --help-types will show a list of types your ack installation supports.