Suspend computer after X minutes

sleeptimer.sh

#!/bin/bash
#
# sleeptimer.sh
#
# Author: Timothy A.V. Teatro <[email protected]>
# Date  : Jan 11, 2011
#
# Description: A rather unsophisticated little script that I wrote for
#    myself. Since I usually fall asleep listening to gnaural or watching
#    a movie on my computer beside my bed, I wanted something to suspend
#    my computer rather than using shutdown.
#
# Usage : sudo ./sleeptimer <integer>
#    where <integer> is the number of minutes before the computer is suspended
#
#    This script is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#####################################################

#
# Must be run as root, so check id at the door.
#
if [ "$(id -u)" != "0" ]; then
	echo Must be run as root.
	exit 1
fi

min=$1 # Keep the first argument on the command line here
elapsed=0 

#
# Check to be sure argument is a number...
#
if [ $min -eq $min 2> /dev/null ]; then
	#
	# ... and if it is, then decide what to do with it
	#
	# If it's less than 15 minutes, we want to count down to 10, 5 and
	# then 1 minute for feedback to the user.
	#	
	if [ $min -lt 15 ]; then
		echo Sleeping in $min minutes [`date`]
		while [ $elapsed -le $min ]; do
			sleep 1m
			elapsed=$((elapsed+1))
			if [ $((min-elapsed)) -eq 10 ]; then
				echo Sleeping in 10 min.
			elif [ $((min-elapsed)) -eq 5 ]; then
				echo Sleeping in 5 min.
			elif [ $((min-elapsed)) -eq 1 ]; then
				echo Sleeping in less than 1 min.
			fi
		done
	else # If it's more, we'll count down in 15 minute intervals.
		#
		# Get the remainder of $min/15 and sleep that down.
		#
		remainder=`expr $min % 15`
		sleep ${remainder}m
		elapsed=$((elapsed+remainder))
		#
		# Now that the time remaining is a factor of 15, we'll sleep
		# in 15 minute incriments until the last 15 minutes of the
		# timer.
		#
		while [ $elapsed -lt $((min-15)) ]; do
			sleep 15m
			elapsed=$((elapsed+15))
			echo Sleeping in $((min-elapsed)) minutes. [`date`]
		done
		sleep 5m
		echo Sleeping in 10 minutes
		sleep 5m
		echo Sleeping in 5 minutes
		sleep 4m
		echo Sleeping in less than a minute.
		sleep 1m
	fi
	#
	# We've done our counting, now suspend.
	#
	echo "!!! NOW SUSPENDING YOUR MACHINE !!!"
	pm-suspend
	exit 0
else
	echo $min is not an integer. Please specify the number of minutes before sleep.
	exit 2
fi