Re: [Xen-devel] drjones@xxxxxxxxxx, vkuznets@xxxxxxxxxx, leiwang@xxxxxxxxxx, wshi@xxxxxxxxxx

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2014-04-24 at 10:01 +0100, George Dunlap wrote:
> On 04/24/2014 09:44 AM, Ian Campbell wrote:
> > On Thu, 2014-04-24 at 08:14 +0800, Lingfei Kong wrote:
> >> Maybe another solution is to change the xl command to adapt this.
> > Feel free to propose a patch but I suspect this would involve too much
> > surgery to the config file parser.
> >
> >>   On
> >> RHEL5 xen hypervisor, I can create a guest with `xm create hvm.cfg
> >> cpus="0-3"`. As a user I prefer this method, because this will be
> >> consistent with it's config file and it is strange to use ' to enclose
> >> the parameters.
> > That is perfectly normal shell quoting behaviour, nothing strange about
> > it IMHO.
> 
> Well having the config file syntax include quotes and brackets is 
> natural.  The fact that the shell interprets quotes and brackets is also 
> natural.  But the combination of the two leads to a rather unexpected 
> and clunky user interface.

This happens all the time though, "in find -exec foo \;" in sed and perl
-e etc etc. It's just the way Unix shells work.

> Unfortunately I'm not sure what we can really do at this point to 
> maintain the general flexibility while avoiding backticks.

Hang on, how did we end up with backticks here? I think you just means
normal quotes?

>   We might be 
> able to modify the parser for specific cases, such as the cpus one, to 
> tolerate 'cpus=0-3' rather than the canonical 'cpus="0-3"'. But in the 
> general case it would require re-writing the config format such that it 
> can be written without requiring any characters treated specially by the 
> shell; that's just a bit more work than it's really worth, I think.

Yes, it isn't worth it IMHO either.

Ian


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