Re: [Xen-devel] [PATCH v1 12/12] hotplug/Linux: add iscsi block hotplug script

[Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>]

Roger Pau Monne writes ("Re: [Xen-devel] [PATCH v1 12/12] hotplug/Linux: add 
iscsi block hotplug script"):
> On 13/03/13 17:31, Ian Jackson wrote:
> > Would it be possible for the user to specify the file that the
> > password should be read from ?
> 
> AFAIK no, this is read from a system defined file, that can be different
> depending on the distro used. Maybe be could expand this script latter
> if needed, in order to be able to detect where this file resides and use
> that instead of passing the user/password in the command line.

Right, fair enough.

> > Did you write this script from scratch ?  (TBH I don't intend to
> > review it in detail...)
> 
> I've found a previous version of iSCSI and Xen here:
> 
> http://backdrift.org/xen-block-iscsi-script-with-multipath-support
> 
> but I didn't use it, so yes.

Right.

> > Why no set -e ?
> 
> Because some of the executed commands might fail, but that's expected
> (and shouldn't abort the execution) and we manually check for the return
> value of executed commands.

I would normally turn on set -e, and then deal explicitly with the
commands that are expected to fail, with patterns like
   set +e
   command that might fail
   rc=$?
   set -e
or
   command we don't care about ||:
or
   if command
   then ...

That avoids accidentally missing out error checking.

Ian.

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