#!/bin/dash
i=0
while true; do
	read -p "Ready to scan. Scan your item(s)? y/N " yn
	case $yn in
		[Yy]* ) scanimage --format=png > ${i}scan.png; i=$(($i+1));;
		[Nn]* ) exit;;
		* ) printf "Please answer yes or no. ";;
	esac
done