Xen devel - May 2010 - [PATCH] xend: update init script to avoid grep on non-existent file system

I''m seeing a grep error during bare metal pvops kernel boot.  In the 
init script, the previous checks will avoid/perform the /proc/xen mount 
as appropriate, but then it does a grep on /proc/xen/capabilities 
without ensuring that /proc/xen is actually mounted.  This is my attempt 
(read: first patch :) ) to avoid it.


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On 15/05/2010 05:16, "Richie" <listmail@triad.rr.com> wrote:
> I''m seeing a grep error during bare metal pvops kernel boot.  In
the
> init script, the previous checks will avoid/perform the /proc/xen mount
> as appropriate, but then it does a grep on /proc/xen/capabilities
> without ensuring that /proc/xen is actually mounted.  This is my attempt
> (read: first patch :) ) to avoid it.
Richie,

Can you try adding the -s option to grep instead (i.e., grep -qs)? Should be
a simpler way to achieve the same thing. I''ll apply that instead if it
works
okay for you.

 -- Keir



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Sure. I agree much simpler, but is this blurb in the grep manpage a concern?
-s, --no-messages
Suppress error messages about nonexistent or unreadable files.
Portability note: unlike GNU grep, 7th Edition Unix grep did not
conform to POSIX, because it lacked -q and its -s option behaved
like GNU grep’s -q option. USG-style grep also lacked -q but
its -s option behaved like GNU grep. *Portable shell scripts
should avoid both -q and -s and should redirect standard and
error output to /dev/null instead*. (-s is specified by POSIX.)

I''m not sure where all the xend daemon can run? is it always running on
linux, thus implying (modern?) GNU grep? The reason I am bringing this 
up is that I recall having grep related issues when running git on 
Solaris (without gnu utilities installed) for this very reason. I will 
re-sumbit accordingly.


Keir Fraser wrote:
> On 15/05/2010 05:16, "Richie" <listmail@triad.rr.com>
wrote:
>
>   
>> I''m seeing a grep error during bare metal pvops kernel boot. 
In the
>> init script, the previous checks will avoid/perform the /proc/xen mount
>> as appropriate, but then it does a grep on /proc/xen/capabilities
>> without ensuring that /proc/xen is actually mounted.  This is my
attempt
>> (read: first patch :) ) to avoid it.
>>     
>
> Richie,
>
> Can you try adding the -s option to grep instead (i.e., grep -qs)? Should
be
> a simpler way to achieve the same thing. I''ll apply that instead
if it works
> okay for you.
>
>  -- Keir
>
>
>   

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On 15/05/2010 15:56, "Richie" <listmail@triad.rr.com> wrote:
> 
> I''m not sure where all the xend daemon can run? is it always
running on
> linux, thus implying (modern?) GNU grep? The reason I am bringing this
> up is that I recall having grep related issues when running git on
> Solaris (without gnu utilities installed) for this very reason. I will
> re-sumbit accordingly.
Well, it''s a Linux-specific hotplug script thet you''re
editing, isn''t it.

 -- Keir



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Keir Fraser wrote:
> On 15/05/2010 05:16, "Richie" <listmail@triad.rr.com>
wrote:
>
>   
>> I''m seeing a grep error during bare metal pvops kernel boot. 
In the
>> init script, the previous checks will avoid/perform the /proc/xen mount
>> as appropriate, but then it does a grep on /proc/xen/capabilities
>> without ensuring that /proc/xen is actually mounted.  This is my
attempt
>> (read: first patch :) ) to avoid it.
>>     
>
> Richie,
>
> Can you try adding the -s option to grep instead (i.e., grep -qs)? Should
be
> a simpler way to achieve the same thing. I''ll apply that instead
if it works
> okay for you.
>
>  -- Keir
>
>
>   


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