On Tue, May 22, 2018 at 3:30 PM, Warner Losh <i...@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.


>
>
> On Tue, May 22, 2018 at 7:57 AM, Johannes Lundberg <johal...@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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