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Re: [Xen-devel] [PATCH v4 3/4] libxl: call hotplug scripts from libxl for vbd

Ian Campbell writes ("Re: [Xen-devel] [PATCH v4 3/4] libxl: call hotplug 
scripts from libxl for vbd"):
> On Mon, 2012-05-14 at 13:38 +0100, Roger Pau Monne wrote:
> > Are you sure about this? This command never returns anything, because it 
> > is redirected to /dev/null, so we only evaluate if it is able to read 
> > libxl/disable_udev. If libxl/disable_udev exists this test is passed.
> You don't need the backticks for that though. With the backticks it will
> execute whatever happens to be in the key -- I guess it's something
> quite benign right now or you'd have seen errors.

In fact Roger was right on the narrow point: because the >/dev/null is
inside the backticks, the backticks never see any output and it's
equivalent to `false` or `true`.  I'm pleased that it's not just me
that read it the way you did at first :-).

But you are of course right in that it's a silly construction.  If the
output is not wanted, `` should not be used.


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