On Thursday, April 14, 2011 19:54:36 Lennart Poettering wrote: > On Thu, 14.04.11 16:15, "Jóhann B. Guðmundsson" (johannbg@xxxxxxxxx) wrote: > > > > > On 04/14/2011 03:36 PM, Lennart Poettering wrote: > > >> In man systemd.unit > > >> > > > >> > BindTo= > > >> > Configures requirement dependencies, very similar in style > > >> > to Requires=, however in addition to this behaviour it also > > >> > declares that this unit is stopped when any of the units > > >> > listed suddenly disappears. Units can suddenly, unexpectedly > > >> > disappear if a service terminates on its own choice, a > > >> > device is unplugged or a mount point unmounted without involvement of > > >> > systemd. > > >> > > > >> > ExecStop=-/bin/systemctl stop upsd-device.service > > >> > ExecStop=-/bin/systemctl stop upsd-monitor.service > > > Why ExecStop= here? > > > > It was meant as an either or. > > > > The BindTo= reference in the man page does not mention that it will take > > down with it any service bound to it when the service is stop. > > Requires= and BindTo= both do that. > > The difference between the two switches is mostly an ordering issue: > > Let's say you have a unit A and a unit B. B requires A, and should be > started after A is up. So in B you say: > > Requires=A > After=A Why is "After=" required here? If B Requires A it seem obvious that B should be started After A (if there is no socket magic). > > now, if you shut down A with "systemctl stop A", this will also stop B, > and it will do so in the inverse starting order. i.e. stop B first, stop > A second. BindTo= would do exactly the same here. The difference now > comes if for some reason A dies independently of anybody running > "systemctl stop A": should we then shut down B retroactviely? The > ordering would normally suggest that B goes down before A, but if A just > goes away on its own, then should we still shut down B? If you use > BindTo= that's what would happen. If you use Requires= it wouldn't. That's not exactly what I'd like to know. Lets say there are services A and B. When B is started, A must be running, so B requires A, but when B is stopped, it should stop A. So A is started only on demand, but it should not be running if there is nothing that requires it. -- devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/devel
