systemd clarification

[Mike Jones]

Bruno,

A related question.

When I look through the services and targets installed when including meta-phosphor, power on/off seems to lead to dead ends, meaning no exe to do the work.

So I looked at meta-facebook, and it adds host-poweron.service, which calls exec power-util…

So it seems to me that meta-phosphor only puts in the infrastructure, and a particular use/design requires adding services to do the actual work of power on/off. This seems logical wrt factoring out behaviors. Is this correct?

This would mean in my cause of use meta-raspberrypi, I need to add the missing pieces if I want power control of my externally connected regulators to get powered on/off.

Mike

> On Aug 25, 2020, at 10:52 AM, Bruno Cornec <Bruno.Cornec at hpe.com> wrote:
> 
> Hello,
> 
> /etc/systemd is used to override or add locally units which are not delivered as part of the std systemd delivery which is under /lib/systemd (or /usr/lib/systemd depending on Linux distribuions). It's an easy way to modify a std unit file and change say the options used to start the daemon e.g.
> So:
> 
> Mike Jones said on Tue, Aug 25, 2020 at 10:20:54AM -0600:
>> The lib path is not a search path in the systemd documentation, and the etc path has links into the lib path. So I assume services in the lib path are only run if they are linked into the etc path. Is this correct?
> 
> No. they are run if they are enabled (systemctl list-units to see that)
> 
>> If there is a an After= that lists something found only in the lib path, I assume it will run because After is not strong enough to prevent start. But if it was Requires=, then I assume it cannot start unless it is linked into the etc path so that it is available. Is this correct?
> 
> No. No link is necessary. 
> Best regards,
> Bruno.
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