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Date: Wed, 21 Mar 2012 13:15:10 +0100
From: Ingo Molnar <mingo@kernel.org>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Jiri Olsa <jolsa@redhat.com>, acme@redhat.com, mingo@elte.hu,
        paulus@samba.org, cjashfor@linux.vnet.ibm.com, fweisbec@gmail.com,
        linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 3/3] perf, tool: Add new event group management
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* Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:

> On Wed, 2012-03-21 at 10:52 +0100, Ingo Molnar wrote:
> > * Peter Zijlstra <a.p.zijlstra@chello.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