dracut-shutdown.service(8) centos man page | unix.com

DRACUT-SHUTDOWN.S(8)						      dracut						      DRACUT-SHUTDOWN.S(8)

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 filesytem can be
       safely unmounted.

       The following steps are executed during a shutdown:

       o   systemd switches to the shutdown.target

       o   systemd starts /lib/systemd/system/shutdown.target.wants/dracut-shutdown.service

       o   dracut-shutdown.service executes /usr/lib/dracut/dracut-initramfs-restore which unpacks the initramfs to /run/initramfs

       o   systemd finishes shutdown.target

       o   systemd kills all processes

       o   systemd tries to unmount everything and mounts the remaining read-only

       o   systemd checks, if there is a /run/initramfs/shutdown executable

       o   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.

       o   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

AUTHORS
       Harald Hoyer

SEE ALSO
       dracut(8)

dracut								    09/12/2013						      DRACUT-SHUTDOWN.S(8)