systemd-update-done.service, systemd-update-done — Mark /etc/ and /var/ as fully updated
systemd-update-done.service
/usr/lib/systemd/systemd-update-done
systemd-update-done.service is a
service that is invoked as part of the first boot after the vendor
operating system resources in /usr/ have been
updated. This is useful to implement offline updates of
/usr/ which might require updates to
/etc/ or /var/ on the
following boot.
systemd-update-done.service updates the file modification time (mtime) stored
in and "on" the files /etc/.updated and /var/.updated to the
modification time of the /usr/ directory, unless the stamp files are already newer.
(The timestamp is stored as the mtime field on the file, but also in the file
to support filesystems that do not store full timestamp precision.)
Services that shall run after offline upgrades of
/usr/ should order themselves before
systemd-update-done.service, and use the
ConditionNeedsUpdate= (see
systemd.unit(5))
condition to make sure to run when /etc/ or
/var/ are older than /usr/
according to the modification times of the files described above.
This requires that updates to /usr/ are always
followed by an update of the modification time of
/usr/, for example by invoking
touch(1)
on it.
Note that if the systemd.condition_needs_update= kernel command line option is
used it overrides the ConditionNeedsUpdate= unit condition checks. In that case
systemd-update-done.service will not reset the condition state until a follow-up
reboot where the kernel switch is not specified anymore.