[systemd-devel] How to start unit before everything else on shutdown

[Mantas Mikulėnas]

On Wed, Nov 26, 2014 at 11:06 PM, Nikolaus Rath <Nikolaus at rath.org> wrote:

> Hello,
>
> I'd like to start a unit on system shutdown and reboot, but do so
> immediately after the "systemctl reboot" command is executed, before any
> other units are terminated.
>

Out of curiosity, what does your unit do? Is there a specific reason for it
to be absolutely first?


> Is there a way to do that?
>

Not easily, I'd guess. (What would happen if two programs asked to be
"absolutely first"?)


> At first I thought that Before=shutdown.target might work, but thinking
> about it, I think this just means that my unit will be started before
> shutdown.target has been reached, but jobs to terminate other units may
> be started before my unit. Is that correct?
>

 I think you'd need the unit to be After all regular units, have an empty
ExecStart, and do its thing in ExecStop. So it'd be started after
everything else, do nothing, and be stopped before everything else.

-- 
Mantas Mikulėnas <grawity at gmail.com>
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