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|
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:
* The system starts to shut down
* ``$prefix/lib/systemd/system/sysinit.target.wants/dracut-shutdown.service``
gets its ``ExecStop`` target triggered.
* ``dracut-shutdown.service`` executes
``/usr/lib/dracut/dracut-initramfs-restore`` which unpacks the initramfs to
``/run/initramfs``
* 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 unmount 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
SEE ALSO
--------
*dracut*(8)
|
