[Techtalk] real life kewl text-processing and regexps samples wanted

[Julie]

Daniel wrote:
> On Fri, Jan 09, 2004 at 07:14:51PM -0800, Elena Bevell wrote:
> 
>>I like this recursive grep that I found somewhere:
>>
>>find  . -type f -exec grep "thing-to-find" {} \;
> 
> 
> This works, but it is horribly slow.
> 
>   find . -type f -print0 | xargs -0 grep "thing-to-find"
> 
> is a lot faster. The first one forks and execs' on every file it
> finds. The second one gives grep dozens of files, without the
> fork and exec overhead.
> 
> But there is a difference, if you call grep on more than one
> file, the filename is prefixed to the search results. If you
> don't want this, use:
> 
>   find . -type f -print0 | xargs -0 cat | grep "thing-to-find"

And there's the opposite problem -- if you do want the name
and you're using xargs to insure you get it, you might not if
the last invocation of "grep" is made with just a since file.
In which case you might do something like

	find . -type f -print | xargs grep foo /dev/null

The extra /dev/null makes it so that grep always has two files
to process.  This is really handy for people who don't have a
grep which includes an option to include the file name
regardless of the number of arguments.
-- 
Julianne Frances Haugh             Life is either a daring adventure
txjulie at austin.rr.com                  or nothing at all.
					    -- Helen Keller