[systemd-devel] howto handle one time shutdown programs

[Andrei Borzenkov]

On Tue, Jun 30, 2015 at 2:35 PM, Andreas Buschmann <buschman at tech.net.de> wrote:
> Hello Johannes,
>
> On Thu 25-Jun-2015 20:09 CEST Johannes Ernst writes:
>
>>> On Jun 25, 2015, at 7:57, Andreas Buschmann <buschman at tech.net.de> wrote:
>>>
>>> I am writing a systemd .service file to handle NVDIMMs.
>>>
>>> - start
>>> - stop
>>> - reload
>>> all work
>>>
>>> The problem child is "restart".
>>> Restart is internally implemented as stop followed by start.
>>>
>>> The problem is, that stop calls a program which does something to the
>>> NVDIMM hardware.
>>> After that no further access to the NVDIMMs is possible before the next
>>> reboot of the server.
>>>
>>> How should I handle that sort of logic with systemd?
>>
>> How is that different from the user executing:
>>
>> systemctl start your.service
>> systemctl stop your.service
>> systemctl start your.service
>>
>> without reboot?
>
> It is not different, but that sequence can not work with my
> implementation of the service.
>
> systemctl stop your.service
> can only be called once.
>
> My stop script shuts down the hardware.
> Think like parking a hard disk.
>
>
> I am not sure on how to do that the systemd way.
>
> I have no problem with spliting the service up into
> myservice1 and myservice2, but than myservice2 has to be called exactly
> once before a shutdown or a reboot completes.
>

You could place separate shutdown hook in
/usr/lib/systemd/system-shutdown/. Note that all executables there are
run concurrently in case it matters.