On Fri, Mar 08, 2019 at 06:38:32PM +0100, Arnt Karlsen wrote:

[cut]

>
> > > I don't seem to have it and everything works without it.
> >
> > It's on my beowulf installations, and I didn't even know that it was
> > there :-/
>
> ..quick starting point:
> ll /proc/sys/kernel/random/boot_id /etc/hostid /etc/machine-id \
> /var/lib/dbus/machine-id /var/db/dbus/machine-id
>

$ ll
bash: ll: command not found
$

:P

anyway:

- /etc/hostid is defined in POSIX 2001 and POSIX 2008 (man gethostid)

- /proc/sys/kernel/random/boot_id is randomly generated by the kernel
at each boot (see drivers/char/random.c and kernel/sysctl.c in the
kernel tree)

- /var/lib/dbus/machine-id is used by dbus, and at the moment seems to
not being re-generated at each boot (my recollection was wrong: we
will fix it)

- /etc/machine-id should be used only by systemd components.

My2Cents

KatolaZ

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