modules.d/98dracut-systemd/dracut-shutdown.service.8.asc

   1 DRACUT-SHUTDOWN.SERVICE(8)
   2 ===========================
   3 :doctype: manpage
   4 :man source:   dracut
   5 :man manual:   dracut
   6
   7 NAME
   8 ----
   9 dracut-shutdown.service - unpack the initramfs to /run/initramfs
  10
  11 SYNOPSIS
  12 --------
  13 dracut-shutdown.service
  14
  15 DESCRIPTION
  16 -----------
  17 This service unpacks the initramfs image to /run/initramfs.
  18 systemd pivots into /run/initramfs at shutdown, so the root filesystem
  19 can be safely unmounted.
  20
  21 The following steps are executed during a shutdown:
  22
  23 * systemd switches to the shutdown.target
  24 * systemd starts /lib/systemd/system/shutdown.target.wants/dracut-shutdown.service
  25 * dracut-shutdown.service executes /usr/lib/dracut/dracut-initramfs-restore which unpacks the initramfs to /run/initramfs
  26 * systemd finishes shutdown.target
  27 * systemd kills all processes
  28 * systemd tries to unmount everything and mounts the remaining read-only
  29 * systemd checks, if there is a /run/initramfs/shutdown executable
  30 * 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.
  31 * shutdown will try to umount every /oldroot mount and calls the various shutdown hooks from the dracut modules
  32
  33 This ensures, that all devices are disassembled and unmounted cleanly.
  34
  35 To debug the shutdown process, you can get a shell in the shutdown procedure
  36 by injecting "rd.break=pre-shutdown rd.shell" or "rd.break=shutdown rd.shell".
  37 ----
  38 # mkdir -p /run/initramfs/etc/cmdline.d
  39 # echo "rd.break=pre-shutdown rd.shell" > /run/initramfs/etc/cmdline.d/debug.conf
  40 # touch /run/initramfs/.need_shutdown
  41 ----
  42
  43 In case the unpack of the initramfs fails, dracut-shutdown-onfailure.service
  44 executes to make sure switch root doesn't happen, since it would result in
  45 switching to an incomplete initramfs.
  46
  47 AUTHORS
  48 -------
  49 Harald Hoyer
  50
  51 SEE ALSO
  52 --------
  53 *dracut*(8)