On Mon, 15 Jun 2015 14:43:30 +0000
Roger Leigh <rleigh@???> wrote:

> On 15/06/2015 14:35, Steve Litt wrote:
> > On Mon, 15 Jun 2015 08:46:13 +0100
> > Arnt Gulbrandsen <arnt@???> wrote:
> >
> >
> >> I really appreciate upstart's way of declaring "start x after y".
> >> (I believe systemd does the same, which I would like if it weren't
> >> one of 500 features.)
> >
> > I've been confused about this for a long time.
> >
> > I know that every service has a "provides", that basically gives the
> > service a uniformly agreed upon name. And it has zero to many
> > "requires", which I believe means that the current service (call it
> > A), requires another service (call it B), so it won't start A
> > unless B is started. But then what does "after" mean? Does that
> > mean *immediately* after, or does that mean *sometime* after, and
> > if the latter, how is that different than "requires"?
>
> It's not that much different AFAIK.
>
> The LSB header specification also had an extension to do this
> (X-Start-Before and X-Stop-After). These are no different to
> Required-Start/Required-Stop except for the fact that the dependency
> is reversed. When it comes to constructing the directed dependency
> graph, these edges are inserted backwards so they end up being
> semantically the same--just a different way of having a different
> package provide the same input to the graph. When you flatten the
> graph to get the ordered/parallelised lists, it's all the same.

Thanks Roger,

Just so I understand your answer in relation to my question, you're
saying that "Start after" means "start sometime after", not "start
immediately after". Right?

SteveT

Steve Litt
June 2015 featured book: The Key to Everyday Excellence
http://www.troubleshooters.com/key