Nut upsuser - May 2013 - placement of ups shutdown command for snmp systems

Hi,
?
on Debian and maybe other systems one of the last steps the system's
shutdown procedure does is to shut down the UPS via upsdrvctl to turn off the
machine and to conserve power.? But this is a place where network communications
via SNMP is not possible anymore because the interfaces are down.
?
So, I am looking for a good place where I can turn off the UPS.? In upsmon.conf
there is the SHUTDOWNCMD.? Currently this is something like "/sbin/shutdown
-h +0".? I thought I could change that to a shell script that sends the UPS
a shutdown with delay command (90sec) and then immediately runs the
"/sbin/shutdown -h +0" command.
?
In the shutdown procedure that is initiated via shutdown -h +0 is there any
point where the shutdown could be interrupted due to power coming back or is
this the final command that always results in the machine being brought down?? I
looked through the scripts that are involved and found nothing.? So my thoughts
are that this is a safe place for the ups shutdown command.
?
Thank for hints, tips, ideas and comments!
?
-lutzn
?
?

>> In the shutdown procedure that is initiated via shutdown -h +0 is there
any point where the shutdown could be interrupted due to power coming back or is
this the final command that always results in the machine being brought down? I
looked through the scripts that are involved and found nothing. So my thoughts
are that this is a safe place for the ups shutdown command.
>
> I haven't looked at the shutdown procedure recently, but the most
common way for an UPS to avoid a race condition when the power comes back is as
follows: once the UPS receives the shutdown command from NUT, it will always cut
power at the scheduled time, even if only momentarily. If line power has
returned, momentarily interrupting the UPS output will break the computer out of
its halted state. If not, then the UPS simply powers off the output, and waits
for line power to return.
>
> I admit that we haven't kept good records on which UPSes do this, but
it is fairly straightforward to test, and it should work on all but the cheapest
models.
Hi,
this is exactly what I currently do.
The question is if this nut shutdown script is the right place to put in the
shutdown -h +0 or if I should use triggers or fiddle with the scheduler or ...
and place it there.
Cheers!
-lutzn