nixpkgs/modules/system/upstart-events/shutdown.nix

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{ config, pkgs, ... }:
with pkgs.lib;
{
jobs.shutdown =
{ name = "shutdown";
task = true;
stopOn = ""; # must override the default ("starting shutdown")
environment = { MODE = "poweroff"; };
extraConfig = "console owner";
script =
''
set +e # continue in case of errors
${pkgs.kbd}/bin/chvt 1
exec < /dev/console > /dev/console 2>&1
echo ""
if test "$MODE" = maintenance; then
echo "<<< Entering maintenance mode >>>"
else
echo "<<< System shutdown >>>"
fi
echo ""
export PATH=${pkgs.utillinux}/bin:${pkgs.utillinux}/sbin:$PATH
# Do an initial sync just in case.
sync
# Kill all remaining processes except init and this one.
echo "sending the TERM signal to all processes..."
kill -TERM -1
sleep 1 # wait briefly
echo "sending the KILL signal to all processes..."
kill -KILL -1
# If maintenance mode is requested, start a root shell, and
# afterwards emit the "startup" event to bring everything
# back up.
if test "$MODE" = maintenance; then
echo ""
echo "<<< Maintenance shell >>>"
echo ""
${pkgs.pam_login}/bin/login root
initctl emit -n startup
exit 0
fi
# Set the hardware clock to the system time.
echo "setting the hardware clock..."
hwclock --systohc --utc
# Unmount helper functions.
getMountPoints() {
cat /proc/mounts \
| grep -v '^rootfs' \
| sed 's|^[^ ]\+ \+\([^ ]\+\).*|\1|' \
| grep -v '/proc\|/sys\|/dev'
}
getDevice() {
local mountPoint=$1
cat /proc/mounts \
| grep -v '^rootfs' \
| grep "^[^ ]\+ \+$mountPoint \+" \
| sed 's|^\([^ ]\+\).*|\1|'
}
# Unmount file systems. We repeat this until no more file systems
# can be unmounted. This is to handle loopback devices, file
# systems mounted on other file systems and so on.
tryAgain=1
while test -n "$tryAgain"; do
tryAgain=
for mp in $(getMountPoints); do
device=$(getDevice $mp)
echo "unmounting $mp..."
# We need to remount,ro before attempting any
# umount, or bind mounts may get confused, with
# the fs not being properly flushed at the end.
# `-i' is to workaround a bug in mount.cifs (it
# doesn't recognise the `remount' option, and
# instead mounts the FS again).
mount -n -i -o remount,ro "$mp"
# Note: don't use `umount -f'; it's very buggy.
# (For instance, when applied to a bind-mount it
# unmounts the target of the bind-mount.) !!! But
# we should use `-f' for NFS.
if umount -n "$mp"; then
if test "$mp" != /; then tryAgain=1; fi
fi
# Hack: work around a bug in mount (mount -o remount on a
# loop device forgets the loop=/dev/loopN entry in
# /etc/mtab).
if echo "$device" | grep -q '/dev/loop'; then
echo "removing loop device $device..."
losetup -d "$device"
fi
done
done
# Final sync.
sync
# Either reboot or power-off the system.
if test "$MODE" = reboot; then
echo "rebooting..."
sleep 1
exec reboot -f
else
echo "powering off..."
sleep 1
exec halt -f -p
fi
'';
};
}