dracut-shutdown.service − unpack the initramfs to /run/initramfs
dracut−shutdown.service
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:
• 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
Harald Hoyer
dracut(8)