yesno() {
shopt -s extglob
unset var
YES='[Yy]?([Ee][Ss])'
NO='[Nn]?([Oo])'
while [[ "$var" != $YES && "$var" != $NO ]]
do
        read var

        case $var in
        $YES)
                return 0
        ;;
        $NO)
                return 1
        ;;
        esac
done
}


echo -e Test?
yesno
if [ -n "$?" ]
then
        echo No
else
        echo Yes
fi