Host ID.

Andrew Pantyukhin infofarmer at
Sat Apr 7 13:35:26 UTC 2007

On 4/7/07, Pawel Jakub Dawidek <pjd at> 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.

Just random thoughts:

- It sounds more like a (writeable) root fs ID...
- Is Windows-style hardware ID's hashing totally ruled out?
- How does it work in other OS'es? (e.g. solaris /bin/hostid)

Anyway, it would be a nice feature. It can be leveraged
in many cases.


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