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dracut-shutdown.service.8.asc

DRACUT-SHUTDOWN.SERVICE(8)
===========================
:doctype: manpage
:man source:   dracut
:man manual:   dracut

NAME
----
dracut-shutdown.service - unpack the initramfs to /run/initramfs

SYNOPSIS
--------
dracut-shutdown.service

DESCRIPTION
-----------
This service unpacks the initramfs image to /run/initramfs.
systemd pivots into /run/initramfs at shutdown, so the root filesystem
can be safely unmounted.

The following steps are executed during a shutdown:

* systemd switches to the shutdown.target
* systemd starts /lib/systemd/system/shutdown.target.wants/dracut-shutdown.service
* dracut-shutdown.service executes /usr/lib/dracut/dracut-initramfs-restore which unpacks the initramfs to /run/initramfs
* systemd finishes shutdown.target
* systemd kills all processes
* systemd tries to unmount everything and mounts the remaining read-only
* systemd checks, if there is a /run/initramfs/shutdown executable
* if yes, it does a pivot_root to /run/initramfs and executes ./shutdown. The old root is then mounted on /oldroot. /usr/lib/dracut/modules.d/99shutdown/shutdown.sh is the shutdown executable.
* shutdown will try to umount every /oldroot mount and calls the various shutdown hooks from the dracut modules

This ensures, that all devices are disassembled and unmounted cleanly.

To debug the shutdown process, you can get a shell in the shutdown procedure
by injecting "rd.break=pre-shutdown rd.shell" or "rd.break=shutdown rd.shell".
----
# mkdir -p /run/initramfs/etc/cmdline.d
# echo "rd.break=pre-shutdown rd.shell" > /run/initramfs/etc/cmdline.d/debug.conf
# touch /run/initramfs/.need_shutdown
----

In case the unpack of the initramfs fails, dracut-shutdown-onfailure.service
executes to make sure switch root doesn't happen, since it would result in
switching to an incomplete initramfs.

AUTHORS
-------
Harald Hoyer