#! /bin/sh
default="$2"
while :
do
	echo "$1 [$default]? " | tr -d '\012' >/dev/tty	# portable echo -n
	read answer
	case "$answer" in
	'')	answer="$default"	;;
	esac
	case "$answer" in
	n*|N*)	answer=no	;;
	y*|Y*)	answer=yes	;;
	esac
	case "$answer" in
	!*)	cmd="`expr \"$answer\" : '!\(.*\)'`"
		trap : 2
		${SHELL-/bin/sh} -c "$cmd" >/dev/tty
		trap 2
		echo '!' >/dev/tty
		;;
	yes|no)	break		;;	# NOTE BREAK OUT
	*)	echo "please answer \`yes' or \`no'" >/dev/tty	;;
	esac
done
echo "$answer"