RE: A note on the use of grep [WAS: Re: HELP! My printer won't stop!!]

["Michael Sims" <michaels@crye-leike.com>]

roberto@familiasanchez.net wrote:
>>> ps aux | grep [l]pr
>>> 
>>> This still lists all the processes that contain the string "lpr",
>>> but it will not match the grep process itself anymore.
>> 
>> Why is that?  Isn't a bracket expression containing only one
>> character exactly the same as the character by itself?  Am I missing
>> something blindingly obvious? :) 
> 
> As you point out, the brackets with one character amount to a range
> of one character.  The "[l]pr" regexp is intrepreted as "lpr", but
> the grep command show up in ps as "grep [l]pr".  This prevents grep
> from matching its own process as it is output by ps.

</me slaps forehead>

Thanks, guess I didn't think hard enough. :)  Nice trick, BTW...