Today I learned a very cool trick. I can grep a pattern inside a given directory by running :grep pattern /path/to/dir. Vim will execute a grep command externally and put the results into a quickfix list.

The quickfix list is basically a dynamic buffer where Vim stores lists of values. In this case, all results returned by the external grep command end up in there, and you can navigate the results by using standard Vim key bindings and pressing Enter.

To access the quickfix list:

:copen " Open the quickfix window
:ccl   " Close it
:cw    " Open it if there are "errors", close it otherwise (some people prefer this)
:cn    " Go to the next error in the window
:cp    " Go to the previous error in the window
:cnf   " Go to the first error in the next file
:.cc   " Go to error under cursor (if cursor is in quickfix window)