[Pacemaker] DRBD Management Console 0.6.0

[Dejan Muhamedagic]

On Tue, Mar 02, 2010 at 07:58:45PM +0100, Lars Ellenberg wrote:
> On Tue, Mar 02, 2010 at 07:28:07PM +0100, Dejan Muhamedagic wrote:
> > Hi,
> > 
> > On Tue, Mar 02, 2010 at 04:19:07PM +0100, Cristian Mammoli - Apra Sistemi wrote:
> > > Lars Ellenberg wrote:
> > > 
> > > >If a "mandatory" parameter has a default,
> > > >then I'd think it is no longer mandatory,
> > > >because, if not specified, it has its default
> > > >to fall back to.
> > > >
> > > >Explicitly specifying a value that happens
> > > >to be the same as the default is fine.
> > > >
> > > >But to _require_ that you explicitly specify
> > > >the default value makes it no longer a default, IMO.
> > > >
> > > >Mandatory paramters in my opinion should be such paramters
> > > >that cannot possibly have a sane default, like the IP for IPaddr2.
> > > 
> > > Got your point, modified the RA to use:
> > > OCF_RESKEY_vimshbin=optional
> > > VIMSHBIN="${OCF_RESKEY_vimshbin-/usr/bin/vmware-vim-cmd}"
> > > 
> > > Thanks to Rasto, didn't know this syntax.
> > 
> > Which syntax is that actually?
> 
> Shell Command Language,
> Parameter Expansion,
>  Using default values.

Aha, that's what he meant. I was actually asking about:

OCF_RESKEY_vimshbin=optional

Somehow it sounded as if that has some special meaning.

> http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06_02
> 
> actually belongs in a frameset:
> http://www.opengroup.org/onlinepubs/9699919799/
> 
> 
> Though iirc, the :- form is not supported by very old sh,
> and the - form may result in unexpected null values...
> More things no-one wants to know about, really ;-)

Indeed.

> A common idiom is:
>   somevar_DEFAULT=my_default
>   somevar=$OCF_RESKEY_somevar
>   : ${somevar:=$somevar_DEFAULT}
> 
> But you knew all that already, of course.

I have to admit that I always have to check what to use to
override empty but set variables.

Cheers,

Dejan

> 	Cheers,
> 
> -- 
> : Lars Ellenberg
> : LINBIT | Your Way to High Availability
> : DRBD/HA support and consulting http://www.linbit.com
> 
> DRBD® and LINBIT® are registered trademarks of LINBIT, Austria.
> 
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