conditonal events to start a script?

[Sean Russell]

On Monday 30 October 2006 16:09, Michael Biebl wrote:
> I agree, that something like this is useful. The problem is, a
> deterministic, dependency based init system does not map one to one
> to an event based init system.

True.

> Even if you have xfs in /etc/event.d/, you can't tell for sure if
> (and when) the start event for xfs is generated and xfs is ever
> started. So what do you do in such a case: wait and then timeout?

I was writing a rebuttal, and then thought of a use case that 
illustrates your point :-)

Just because an service is in the events list, doesn't mean that it will 
ever get an event causing it to either start or fail.  That means that 
my simple solution (that it is satisfied if it starts, fails to start, 
or doesn't exist) is insufficient to cover all scenarios.

That said, I believe that this situation (a service is in the list of 
events but is never triggered) is an edge case, and conditional events 
are still useful following the guidelines I suggested in an earlier 
email.

> >  PS for Gentoo-ers, this is know as 'after'
>
> Not quite correct, the corresponding functionality in Gentoo's init
> is called "use", which describes a conditional dependency (in
> contrary to "need", which is an absolute dep). "before" and "after"
> are mere ordering statements [1].

He was right: it is closer to "after" than "use".  From the Gentoo init 
documentation:

	"In some cases you might not require a service, but want your service 
to be started before (or after) another service if it is available on 
the system"

http://www.gentoo.org/doc/en/handbook/handbook-x86.xml?part=2&chap=4

> Cheers,

Back atcha.

--- SER