Why bracket a single letter in a grep regex?

Question

I've seen several instances where people are doing this:

grep [f]oobar

But I don't understand why that is preferable to

grep foobar

Answer 1

There's no reason that's preferable syntax on its own. It's sometimes used as a hack when "grepping" for a process (e.g., ps aux | grep [a]pache). Using that syntax prevents grep from matching its own command line in the process list.

See How to prevent "ps" reporting its own process?