in-terminal timer shell script

terminalTimer.sh

# script to create timer in terminal
# Jason Atwood
# 2013/6/22
#!/bin/sh

# start up 
echo "starting timer script ..." 
sleep 1 # seconds

# get input from user
read -p "Timer for how many minutes?" -e DURATION
DURATION=$(( $DURATION*60 )) # convert minutes to seconds

# get start time
START=$(date +%s)

# infinite loop
while [ -1 ]; do
	clear					# clear window

	# do math	
	NOW=$(date +%s)				# get time now in seconds
	DIF=$(( $NOW-$START ))			# compute diff in seconds
	ELAPSE=$(( $DURATION-$DIF ))		# compute elapsed time in seconds
	MINS=$(( $ELAPSE/60 ))			# convert to minutes... (dumps remainder from division)
	SECS=$(( $ELAPSE - ($MINS*60) )) 	# ... and seconds

	# conditional
	if [ $MINS == 0 ] && [ $SECS == 0 ]	# if mins = 0 and secs = 0 (i.e. if time expired)
	then 					# blink screen
		for i in `seq 1 180`;    		# for i = 1:180 (i.e. 180 seconds)
		do
			clear					# flash on
			setterm -term linux -back red -fore white # use setterm to change background color
			echo "00:00                             		" # extra tabs for visibiltiy

			sleep 0.5

			clear					# flash off
			setterm -term linux -default		# clear setterm changes from above 
			echo "00:00" 				# (i.e. go back to white text on black background)
			sleep 0.5	
		done  					# end for loop 
		break					# end script

	else 					# else, time is not expired
		echo "$MINS:$SECS"			# display time
		sleep 1  				# sleep 1 second
	fi					# end if
done	# end while loop	

Works great in Gnome shell. Tested in tmux too. Works but doesn't flash entire pane.
Use "setterm -default" to reset colors if terminating program during flashing.

Worked immediately on OSX in iTerm. Thank you!

Can you add options to the end time to play music? PLEASE.

You can make your own beep in linux with

( speaker-test -t sine -f 400 -l 1 >/dev/null & sleep .3 && kill -9 $! );( speaker-test -t sine -f 500 -l 1 >/dev/null & sleep .3 && kill -9 $! );( speaker-test -t sine -f 300 -l 1 >/dev/null & sleep .3 && kill -9 $! )

This does a Do DOO doo sound.

Replace lines 31 to 43 with it