On Thu, Aug 08, 2019 at 11:41:52AM -0400, Marvin Renich wrote:
* Michael Stone <mst...@debian.org> [190808 08:42]:
On Thu, Aug 08, 2019 at 08:37:16AM -0400, Marvin Renich wrote:
> Does anyone know what applications use this file for what purpose? Is
> this a systemd-ism?
man machine-id
The man page says what it is (a unique, random ID for the machine) and
how to initialize it, but says nothing about why it exists. What
applications expect it to be there?
From the man page:
The machine ID does not change based on local or network configuration
or when hardware is replaced. Due to this and its greater length, it
is a more useful replacement for the gethostid(3) call that POSIX
specifies.
[...]
When a machine is booted with systemd(1) the ID of the machine will be
established. If systemd.machine_id= or --machine-id= options (see
first section) are specified, this value will be used. Otherwise, the
value in /etc/machine-id will be used. If this file is empty or
missing, systemd will attempt to use the D-Bus machine ID from
/var/lib/dbus/machine-id, the value of the kernel command line option
container_uuid, the KVM DMI product_uuid (on KVM systems), and finally
a randomly generated UUID.
