#!/usr/local/bin/bash 
page=0
scale=100
echo $1

while read cmd1 cmd2; do
	if [ -z $cmd1 ]; then
		cmd1="n";
	fi
	if [ "n" == $cmd1 ]; then
		let page=page+1;
	fi 
	if [ "s" == $cmd1 ]; then
		let scale=$cmd2;
	fi 
	
	if [ "j" == $cmd1 ]; then
		let page=page+$cmd2;
	fi 
	if [ ! -z $! ]; then # get rid of viewer window
		kill $!
	fi
	echo displaying page $page
	ddjvu -format=pgm -page=$page -scale=$scale "$1" | xv - &
done