From mboxrd@z Thu Jan  1 00:00:00 1970
To: 9fans@cse.psu.edu
Subject: Re: Plan 9 annoyances (was: Re: [9fans] mv vs cp) 
In-reply-to: Your message of "Tue, 09 Oct 2001 11:55:04 +0100."
             <20011009104245.DE77F19A0F@mail.cse.psu.edu> 
Message-ID: <17563.1002628227@apnic.net>
From: George Michaelson <ggm@apnic.net>
Date: Tue,  9 Oct 2001 21:50:27 +1000
Topicbox-Message-UUID: 02f8f4ce-eaca-11e9-9e20-41e7f4b1d025


> > > i've missed find several times. xargs always struck me as
> > > compensating for poor shell design.
> >
> > Isn't the problem the argv limits of number of characters and number of
> > words?
> 
> i don't think so entirely...
> 
> for instance if i want to grep through an entire source tree,
> i don't want to wait until the tree has been traversed completely
> before the text searching begins. using
> 
> 	du -a . | awk '{print $2}' | xargs grep pattern
> 
> often gives me results much faster than
> 
> 	grep pattern `{du -a . | awk '{print $2}'}
> 

if you had a way to unblock/buffer the pipe, would the diffence be that
great?

That aside, I suspect I prefer the xargs one because my frontal lobes
are wired for linear tape-processing methods, and the second one requires
understanding function theory and/or two passes to parse the nested clause.

> the latter usually works. i don't know what the kernel
> limit is on command-line arguments, but it's more than sufficient
> to pass all the source files in /sys/src (6764 files, ~160K).
> 
>   rog.

Ie if you deliberately avoid the glob expansion problems which bedevill
ls * | do a bunch of stuff you don't need find in flat spaces.

xargs is cheap to implement in a shellscript and I have done that too,
because I didn't know  xargs existed for a long time. Likewise I use awk
'{print $fieldnum}' because I didn't know cut existed, and my erstwhile
younger and wiser heads find me laughably inept at shell these days.

So is this yet another iteration of 'why write a command when you can write
a script' ?

-George

PS amusingly enough, the same year I was learning about v7 on a pdp11
in Leeds, I had an Armenian guy try and convince me PICK was the way of
the future, and that all coming filesystems would be database abstraction.

I suppose if I'd been malleable enough I'd have bought that too. Still,
we all laughed at the head of department for being a laser physicist. "What
could *he* know about computing?" we said. And more fool us...


--
George Michaelson       |  APNIC
Email: ggm@apnic.net    |  PO Box 2131 Milton QLD 4064
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