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

Hmm .. I thought it is supposed to match range of characters within the []. If it is just a single character, it could be just to make it look complicated :) Maybe there is something more to it. — Chida, Aug 22 '12 at 19:45

score 33 · Accepted Answer · edited Apr 13 '17 at 12:14

33

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?

edited Apr 13 '17 at 12:14

Community

1

answered Aug 22 '12 at 19:44

Jeff Ferland

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That's the only common example of that syntax I'm familiar with. – ewwhite Aug 22 '12 at 19:57
In fact, you are right. The last several examples I ran across were from a "ps exclusion" – hortitude Aug 23 '12 at 15:39

Why bracket a single letter in a grep regex?

1 Answers1