#!/bin/bash

# 31.12.2005, Hauke Laging, http://www.hauke-laging.de/, software@hauke-laging.de

# This script switches between reboot and system halt between its calls. 
# If this script is called from the ctrlaltdel line in /etc/inittab 
# then you can switch between reboot and system halt by pressing

# LICENSE
# This code is licensed to you under the GNU General Public License.
# See http://www.fsf.org/

# REQUIREMENTS
# - GNU date.

# USAGE
# You should configure this script and your system so that the variables 
# $check_dir and $check_file together point to a file which does not exist 
# after a reboot. This can be achieved by adding these commands to your 
# boot.local file:
# test -e /var/run/empty_on_reboot && rm -r /var/run/empty_on_reboot
# mkdir -p /var/run/empty_on_reboot

check_dir=/var/run/empty_on_reboot
check_file=ctrl-alt-del
REDIRECT=/dev/tty1
first_action=do_reboot

do_shutdown () {
	test -d "$check_dir" && echo shutdown > "${check_dir}/${check_file}"
	echo $'\n'"The system is being shut down.
Press <Ctrl>-<Alt>-<Del> again for rebooting."$'\n' > $REDIRECT
	sleep 2
	/sbin/telinit q # <Ctrl>-<Alt>-<Del> reaktivieren
	/sbin/shutdown -h -t 4 now
}

do_reboot () {
	test -d "$check_dir" && echo reboot > "${check_dir}/${check_file}"
	echo $'\n'"The system is rebooting.
Press <Ctrl>-<Alt>-<Del> again for powering off."$'\n' > $REDIRECT
	sleep 3
	/sbin/telinit q # <Ctrl>-<Alt>-<Del> reaktivieren
	/sbin/shutdown -h -t 4 now
}

# standard action if the directory does not exist
test -e "$check_dir" || { "$first_action"; exit; }
if [ -f "${check_dir}/${check_file}" ]
	then
	# BEGIN: check if the file is older than the lifetime of the init process
	init_hours=0
	init_days=0
	init_etime=$(echo $(/bin/ps --pid 1 -o etime | sed 1d))
	init_seconds=${init_etime##*:}
	tmp=${init_etime%?????}
	init_minutes=${init_etime#${tmp}}
	init_minutes=${init_minutes%???}
	if [ -n "$tmp" ]
		then
		days_hours=${tmp%:}
		if [ ${#days_hours} -gt 2 ]
			then
			init_days=${days_hours%???}
			init_hours=${days_hours%???}
		else
			init_hours=$days_hours
		fi
	fi
	# COMMENT: These always have two digits
	init_seconds=${init_seconds#0}
	init_minutes=${init_minutes#0}
	# COMMENT: These have two digits only when set from ps output.
	test ${#init_hours} -gt 1 && init_hours=${init_hours#0}
	test ${#init_days} -gt 1 && init_days=${init_days#0}
	init_elapsed_seconds=$((init_seconds+init_minutes*60+init_hours*60*60+init_days*60*60*24))
	if date +%s &>/dev/null # GNU date available?
		then
		seconds_checkfile=$(/bin/date --reference="${check_dir}/${check_file}" +%s)
		seconds_system_currently=$(/bin/date +%s)
		seconds_system_boot=$((seconds_system_currently-init_elapsed_seconds))
		if [ "$seconds_system_boot" -gt "$seconds_checkfile" ]
			then
			"$first_action"
			exit
		fi
	fi
	# END: check if the file is older than the lifetime of the init process
	state="$(cat "${check_dir}/${check_file}")"
else
	"$first_action"
	exit
fi
if [ "$state" = reboot ]
	then
	do_shutdown
else
	echo reboot > "${check_dir}/${check_file}"
	do_reboot
fi