How to check if not clean shutdown?

[Rodney W. Grimes]

> On Tue, May 22, 2018 at 3:30 PM, Warner Losh <imp at bsdimp.com> wrote:
> 
> > You can't, in general. By the time the boot loader starts, all knowledge
> > of past boots is gone, unless specific counter-measures were put in place.
> >
> > However, if root is UFS and read/write in your box, it will be unclean on
> > anything but a clean shutdown/reboot. If it's read-only, ZFS or NFS
> > mounted, then you can't use this method.
> >
> > If you have UEFI, you can set a UEFI variable on shutdown and clear it on
> > boot. If it's not there on boot, you had an unclean shutdown. You could do
> > the same with a file in a r/w filesystem that doesn't record clean/unclean
> > (like ZFS or NFS).
> >
> > Locally, we have hacks to IPMI to record kernel crashes in the IPMI log,
> > but that's kinda specific to the BMC we have on our boards...
> >
> > Warner
> >
> 
> I see. Thanks for the quick reply.
> I guess I can add a dummy file somewhere that I delete in a shutdown hook.

utmp has one attempt at keeping track of this by recording a shutdown record.


> > On Tue, May 22, 2018 at 7:57 AM, Johannes Lundberg <johalun0 at gmail.com>
> > wrote:
> >
> >> Hi
> >>
> >> In the boot process on my test machines I'd like to do different things
> >> depending on the last run was a clean shutdown or kernel panic. Where/How
> >> can I get this information?
> >>
> >> Thanks!
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> >
> >
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-- 
Rod Grimes                                                 rgrimes at freebsd.org