Re: finding .m files using 'locate'

[Mike Miller]

On Mon, 18 Jul 2005, Przemek Klosowski wrote:

> there's a mistake in your regexp:
>
>   s#(^.*)/[^/]+.m#$1#g
>
> the dot before the 'm' should be escaped (the result is OK, but it is
> the kind of problems that trip up even seasoned regexp users).

You are right because I'm sure I mean to put a backslash in there, but I'm 
not sure that it does anything in this context (after "egrep '\.m$'"). 
In fact, I think this would work (dropping the ".m")...

s#(^.*)/[^/]+#$1#g

...because the first '*' is greedy so it takes up the full path.


> Also, I believe your code would fail if there was a directory named 
> /home/dir.m (so would mine, but for a different reason :)

I can't see why my code would fail.  Can you explain that?  This doesn't 
fail:

echo '/home/dir.m' | egrep '\.m$' | perl -pe 's#(^.*)/[^/]+.m#$1#g' | sort | 
uniq


> I agree w/you completely about Perl being the only tool one ever needs 
> ("Swiss army chainsaw"). I have eschewed sed, awk and even egrep; in 
> fact I would have written your
>
> locate .m | egrep '\.m$' | perl -pe 's#(^.*)/[^/]+.m#$1#g' | sort | uniq
> as
> locate .m | perl -ne 'print if s#(^.*)/[^/]+\.m$#$1#' | sort | uniq

Nice.  You know more about this stuff than I do, I'm sure.  (I do know I 
didn't need the 'g' but I didn't think of it.)

But remember the trick we learned about locate.  We can do this...

locate "*.m" | perl -pe 's#(^.*)/[^/]+m#$1#' | sort | uniq

...and leave off the grepping.

Mike



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