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Re: Prompt expansion, multi-job for
- X-seq: zsh-users 2839
- From: Andre Pang <andrep-ml@xxxxxxxxxxx>
- To: Oliver Kiddle <opk@xxxxxxxxxxxxx>
- Subject: Re: Prompt expansion, multi-job for
- Date: Fri, 7 Jan 2000 01:54:33 +1100
- Cc: zsh-users@xxxxxxxxxxxxxx
- In-reply-to: <3874847D.A2ED4AE3@xxxxxxxxxxxxx>; from opk@xxxxxxxxxxxxx on Thu, Jan 06, 2000 at 12:03:09PM +0000
- Mail-followup-to: Oliver Kiddle <opk@xxxxxxxxxxxxx>, zsh-users@xxxxxxxxxxxxxx
- Mailing-list: contact zsh-users-help@xxxxxxxxxxxxxx; run by ezmlm
- References: <20000106194432.A488@xxxxxxxxxxxxxxxxx> <3874847D.A2ED4AE3@xxxxxxxxxxxxx>
- Reply-to: Andre Pang <andrep@xxxxxxxxxxx>
- Sender: andrep@xxxxxxxxxxx
On Thu, Jan 06, 2000 at 12:03:09PM +0000, Oliver Kiddle wrote:
> Andre Pang wrote:
> > 2) Is there any way to emulate make's -jn option in the for command?
> > This would be *really* useful for SMP systems. Currently, doing something
> > like "for i in ***/***.wav; do l3enc $i; done" doesn't take advantage of
> > multiple CPUs (on a Linux system, at least); hacking the for command to
> > accept a 'make -j'-like parameter (eg: for -j2 i in *; do l3enc $i; done)
> > would allow us lucky ones who have SMP systems to do many things similar to
> > the above without going mad and writing silly Makefiles simply so we can
> > utilise make -j. If someone's written a function to do this already (Bart?
> > ;) it'd be *very* cool.
> If I'm not mistaken, you should be able to do this by running l3enc as a
> background process, i.e. for i in *.wav; do l3enc $i& done. I haven't
> got an SMP system available to me to test but I'd assume that it would
> allocate different l3enc processes to different processors. Putting the
Yes, you're right there. I've done this a few times when I've had < 15
jobs to run, but today, I did a 'for i in ***/***.wav; do shorten $i; done',
and I have easily >200 .wavs which I wanted to compress. Running 200
background processes isn't my idea of fun :).
> a maximum of 4 l3encs at once. This would be a bit messy to implement in
> Zsh (compared to something like Ada) but can be done.
Which brings me back to my original question - if someone has a function
to do this already, I'll be most happy. I'm just not sure whether it's
possible to make a function which can emulate the behaviour of the for
command perfectly, because it's treated as a complex command and not as a
function. I'm thinking that the only way to implement this gracefully would
be to either (a) change the syntax of the new function, thus having a for
command with a different syntax - annoying, or (b) modify the zsh source
to deal with it, which I would love to do, but I lack the skill for.
 Perhaps the closest you'd get is ``jfor -2 i in * do 'l3enc -q $i;
echo done $i' done'' -- note the lack of semicolons and the single quotes
around the commands to run. Even then, the syntax is different from normal
for. Syntax change == bad.
: Andre Pang <andrep@xxxxxxxxxxx> - Purruna Pty Ltd - ph# 0411.882299 :
: #ozone - http://www.vjolnir.org/ozone/ :
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