Host ID.

Pawel Jakub Dawidek pjd at
Sat Apr 7 17:55:02 UTC 2007

On Sat, Apr 07, 2007 at 06:47:41PM +0200, Pawel Worach wrote:
> Pawel Jakub Dawidek wrote:
> >Hi.
> >After initial discussion on IRC, I'd like to propose an addition...
> >I want to use it with ZFS, but I thought it may be useful in general, so
> >here it goes:
> >I'd like to assign a unique ID to the system on first boot.
> >When system starts, /etc/rc.d/hostid script checks if /hostid file
> >exists, if it doesn't, it creates it via 'uuidgen > /hostid'.
> >It will also set kern.hostuuid sysctl to this value and first four bytes
> >of MD5(kern.hostuuid) will be stored in kern.hostid. It will allow to
> >use gethostid(3).
> >If root file system is read-only, different uuid will be genrated on
> >each boot. Not sure if anything better can be done here.
> >As I said, I think it may be genrally useful. Imagine using it with
> >magic/variant symlinks, for example.
> >Comments?
> What about ...
> # kenv smbios.system.uuid
> 63F8BC81-475C-11CB-A074-CA3B9005F8F6
> Not all systems have SMBIOSen but maybe it can be used instead of /{,etc}/hostid if available ?

We thought about this, but as you noted it's not always available. I
want this to behave the same on each system.

Pawel Jakub Dawidek             
pjd at                 
FreeBSD committer                         Am I Evil? Yes, I Am!
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