DRACUT\-SHUTDOWN\&.S
Section: dracut (8)
Updated: 02/12/2021
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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:
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systemd switches to the shutdown.target
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systemd starts /lib/systemd/system/shutdown.target.wants/dracut-shutdown.service
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dracut-shutdown.service executes /usr/lib/dracut/dracut-initramfs-restore which unpacks the initramfs to /run/initramfs
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systemd finishes shutdown.target
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systemd kills all processes
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systemd tries to unmount everything and mounts the remaining read-only
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systemd checks, if there is a /run/initramfs/shutdown executable
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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.
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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".
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# 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)