/etc/init.d/umountroot is in initscripts 2.88dsf-13.10ubuntu11.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
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### BEGIN INIT INFO
# Provides: umountroot
# Required-Start:
# Required-Stop:
# Should-Stop: halt reboot kexec
# Default-Start:
# Default-Stop: 0 6
# Short-Description: Mount the root filesystem read-only.
### END INIT INFO
PATH=/sbin:/bin
. /lib/init/vars.sh
. /lib/lsb/init-functions
do_stop () {
[ "$VERBOSE" = no ] || log_action_begin_msg "Mounting root filesystem read-only"
# Ask init to re-exec itself before we go down if it has been
# upgraded this cycle. It'll lose all its state, but at least
# it won't hold open files on the root filesystem (lp:#672177).
if [ -f /var/run/init.upgraded ]
then
old_map=$( cat /proc/1/maps )
map=$old_map
telinit u || :
i=0
timeout=5
while [ "$map" = "$old_map" ]
do
sleep 1
map=$( cat /proc/1/maps )
/usr/bin/logger "waiting for init to respawn"
i=$((i+1))
if [ $i -eq $timeout ] ; then
break
fi
done
if [ "$map" = "$old_map" ] ; then
/usr/bin/logger "FAIL: init failed to respawn in $timeout seconds - unmounting anyway"
else
/usr/bin/logger "SUCCESS: init respawned after $i seconds (within $timeout seconds timeout)"
fi
fi
# These directories must exist on the root filesystem as they are
# targets for system mountpoints. We've just unmounted all other
# filesystems, so either they are mounted now (in which case the
# mount point exists) or we can make the mountpoint.
for dir in /proc /sys; do
mkdir -p $dir || true
done
# These must be turned into symlinks for the /run transition. We
# can't do this at boot time because / is remounted read-write too
# late, so do it on shutdown instead.
if [ -d /var/run ]; then
umount -l /var/run || true
rm -rf /var/run
ln -nsf /run /var/run
fi
if [ -d /var/lock ]; then
umount -l /var/lock || true
rm -rf /var/lock
ln -nsf /run/lock /var/lock
fi
if [ -d /dev/shm ]; then
umount -l /dev/shm || true
rm -rf /dev/shm
ln -nsf /run/shm /dev/shm
fi
if [ ! -L /lib/init/rw ] && umount -l /lib/init/rw && \
rm -rf /lib/init/rw; then
ln -nsf /run /lib/init/rw
elif [ -L /lib/init/rw ] && [ $(readlink /lib/init/rw) != /run ]; then
rm -f /lib/init/rw
ln -nsf /run /lib/init/rw
fi
MOUNT_FORCE_OPT=
[ "$(uname -s)" = "GNU/kFreeBSD" ] && MOUNT_FORCE_OPT=-f
# This:
# mount -n -o remount,ro /
# will act on a bind mount of / if there is one.
# See #339023 and the comment in checkroot.sh
mount $MOUNT_FORCE_OPT -n -o remount,ro -t dummytype dummydev / 2>/dev/null \
|| mount $MOUNT_FORCE_OPT -n -o remount,ro dummydev / 2>/dev/null \
|| mount $MOUNT_FORCE_OPT -n -o remount,ro /
ES=$?
[ "$VERBOSE" = no ] || log_action_end_msg $ES
}
case "$1" in
start)
# No-op
;;
restart|reload|force-reload)
echo "Error: argument '$1' not supported" >&2
exit 3
;;
stop)
do_stop
;;
*)
echo "Usage: $0 start|stop" >&2
exit 3
;;
esac
:
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