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Message-ID: <20120321121510.GA4386@gmail.com>
Date: Wed, 21 Mar 2012 13:15:10 +0100
From: Ingo Molnar <mingo@...nel.org>
To: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Jiri Olsa <jolsa@...hat.com>, acme@...hat.com, mingo@...e.hu,
paulus@...ba.org, cjashfor@...ux.vnet.ibm.com, fweisbec@...il.com,
linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 3/3] perf, tool: Add new event group management
* Peter Zijlstra <a.p.zijlstra@...llo.nl> wrote:
> On Wed, 2012-03-21 at 10:52 +0100, Ingo Molnar wrote:
> > * Peter Zijlstra <a.p.zijlstra@...llo.nl> wrote:
> >
> > > # echo {}
> > > {}
> > > # echo {en,dis}able
> > > enable disable
> > >
> > >
> > > It somehow special cases {}, which is horrible.
> >
> > Oh, indeed: brace expansion and sequence expressions both use
> > curly braces:
> >
> > $ echo foo-{a,b,c}-bar
> > foo-a-bar foo-b-bar foo-c-bar
> >
> > $ echo {1..10}
> > 1 2 3 4 5 6 7 8 9 10
> >
> > Too bad, it would be rather intuitive. All the brace characters
> > are taken by Bash.
> >
> > Maybe something like:
> >
> > $ echo /minor-faults,major-faults/
> > /minor-faults,major-faults/
> >
> > although it looks a bit weird.
> >
> > So ... how about using another grouping operator, such as '+'?
> >
> > Something like:
> >
> > -e minor-faults+major-faults
> >
> > While when comma separated they are not grouped, or so.
>
> I would much prefer a syntax that's more natural but requires
> quoting than one that's quirky and tailor made to avoid
> whatever current bash does. For one, there's other shells out
> there that might have different quoting needs and bash is of
> course free to extend its syntax.
Well, they are unlikely to extend to '+', it would break a
boatload of scripts I suspect.
So the question would be, is a+b+c as event grouping a natural
syntax? If not then lets use a quoted one that is.
Thanks,
Ingo
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