Man page - dracut-shutdown.service(8)

Packages contains this manual

Package:  dracut-core
apt-get install dracut-core

Manuals in package:
• dracut-pre-mount.service(8)
• dracut.cmdline(7)
• dracut-catimages(8)
• dracut.modules(7)
• dracut-shutdown.service(8)
• dracut(8)
• lsinitrd(1)
• dracut-pre-udev.service(8)
• dracut-cmdline.service(8)
• dracut.kernel(7)
• dracut-mount.service(8)
• dracut-initqueue.service(8)
• dracut-pre-trigger.service(8)
• dracut.bootup(7)
• dracut-pre-pivot.service(8)
• dracut.conf(5)
Documentations in package:
• dracut-core

Manual

DRACUT-SHUTDOWN.S

NAME
SYNOPSIS
DESCRIPTION
AUTHORS
SEE ALSO

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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:

• 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)

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