How to start a unit right after another unit terminates?

[arvidjaar@xxxxxxxxx (Andrei Borzenkov)]

16.07.2018 21:32, John Ioannidis пиÑ?еÑ?:
> Assume I have a one-shot service, *phase1.service*, which runs for a while
> and then terminates. I want to have a *phase2.service* start up when phase1
> terminates.
> 
> I cannot change anything in phase1.service's systemd files or code or
> anything, or I would not be asking this question!
> 

Just add After=phase1.service to phase2.service. For oneshot services
startup completes when service ExecStart* commands complete. Request to
start phase2.service will be waiting for that.

> A dirty workaround is to just have phase2 start before phase1 and run this
> script (wait until phase1 starts up, then wait until it finishes, then do
> its thing):
> 
>     while ! systemctl status phase1.service > /dev/null
>     do
>       sleep 10 # still waiting for phase1 to start up
>     done
>     while systemctl status phase1.service > /dev/null
>     do
>       sleep 10 # still waiting for phase1 to finish
>     done
>     # now do the phase2 work
> 
> There has to be a better way of doing this, but I can't figure it out.
> Google/Bing/SO searches return lots of other workarounds, mostly for user
> sessions, which is not the case here.
> 
> Thanks!
> 
> 
> 
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