[Xen-devel] Re: [PATCH 3 of 3] [xen-detect] Add arguments to print out only outputs we are interested in

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 22/12/2009 16:48, "Konrad Rzeszutek Wilk" <konrad.wilk@xxxxxxxxxx> wrote:

> # HG changeset patch
> # User konrad@xxxxxxxxxxxxxxxxxxx
> # Date 1261498156 18000
> # Node ID 04c067941b17bdc679ffdc2f6c81f8e2f78e9cc5
> # Parent  7bd805a543da685a3dba7b8b0c4e3e7052c863b3
> [xen-detect] Add arguments to print out only outputs we are interested in.
> 
> This is quite usefull in scripts where you can do
> if xen-detect -P || modprobe xen-<some module>
> 
> And do not have to parse the output - instead you will get
> the output only if the condition exists.

Er, what? The above shell fragment is affected by the value returned by
xen-detect (0 versus non-0), not by whether it prints something!

Here is my suggestion: keep your new command-line options, but instead of
affecting printing, have them affect the return value. E.g., -P causes
return 0 if running PV, else return 1. Further, we can add a -q option to
quiesce normal output from xen-detect, to make it quieter for use in shell
scripts.

E.g, xen-detect -Pq && modprobe some-xen-pv-specific-module

What do you think of that?

 -- Keir



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