Re: option to continue on exit status 255 (patch incl)

[Scott Sinno]

        I neglected to actually attach the patch.  Here it is. 

On Mon, Aug 11, 2008 at 04:15:57PM -0400, Scott Sinno wrote:
> 
>       This is not a bug report, but rather a feature-request.  Attached
> is a patch to implement the feature.  More below.. 
> 
>       I use xargs routinely to remotely execute commands via ssh on 
> clusters with hundreds of machines.  Almost invariably, one or more
> of the machines I want to issue a remote-command to is offline.  
> Some subset of servers being offline is fairly normal in a large
> data-center. 
> 
>       Of course, when even one machine is offline, attempting to 
> run a remote command on it causes said-command to exit w/code 255,
> in turn causing xargs to cease immediately.  The attached patch
> allows the '-c' flag to be optionally included at execution.
> If it is, xargs will continue on code 255 rather than halting.
> While such behavior might make a rigorous developer recoil in 
> horror, it has immense practical applications as it's simply unreasonable
> to expect all the servers to be online at all times in a large computing
> environment. 
>       
>       I am not a developer, nor do I even play one on TV.  It is
> extremely likely that this patch does things the xargs maintainer(s)
> won't like, for good reason.  I'm hoping someone more familar
> with the xargs code will give this a good lookover, and perhaps
> eventually incorporate this sort of functionality into the
> findutils baseline. 
> 
> #trivial example, with and without '-c' flag provided by patch.
> address@hidden xargs]seq 5004 5006 | awk '{print "minion"$1}' | xargs -t -i 
> ssh -q address@hidden "uname -a"
> ssh -q address@hidden uname -a 
> Linux minion5004 2.6.8.1-26mdksmp #1 SMP Mon Nov 28 12:40:04 MST 2005 i686 
> Intel(R) Xeon(TM) CPU 2.80GHz unknown GNU/Linux
> ssh -q address@hidden uname -a 
> xargs: ssh: exited with status 255; aborting
> 
> #and now with the continue (-c) flag
> address@hidden xargs]seq 5004 5006 | awk '{print "minion"$1}' | ./xargs -c -t 
> -i ssh -q address@hidden "uname -a"
> ssh -q address@hidden uname -a 
> Linux minion5004 2.6.8.1-26mdksmp #1 SMP Mon Nov 28 12:40:04 MST 2005 i686 
> Intel(R) Xeon(TM) CPU 2.80GHz unknown GNU/Linux
> ssh -q address@hidden uname -a 
> ssh: exited with status 255; continuing
> ssh -q address@hidden uname -a 
> Linux minion5006 2.6.8.1-26mdksmp #1 SMP Mon Nov 28 12:40:04 MST 2005 i686 
> Intel(R) Xeon(TM) CPU 2.40GHz unknown GNU/Linux
> 
> -----------------------------------------------------------------------------
> Scott Sinno                           address@hidden
> Systems Engineer              Office : 301-614-5462
> "Bureaucracy is the epoxy that greases the wheels of progress." -Dr. Jim Boren
-----------------------------------------------------------------------------
Scott Sinno                             address@hidden
Systems Engineer                Office : 301-614-5462
"Bureaucracy is the epoxy that greases the wheels of progress." -Dr. Jim Boren

xargs_continue.tar.gz
Description: GNU Zip compressed data