echo "4" > /sys/class/gpio/export echo "out" > /sys/class/gpio/gpio4/direction echo "7" > /sys/class/gpio/export echo "in" > /sys/class/gpio/direction previous=$(cat /sys/class/gpio/gpio7/value) while true do pin=$(cat /sys/class/gpio/gpio7/value) if[ $pin -gt $previous ]; then echo "1" > /sys/class/gpio/gpio4/value else echo "0" > /sys/class/gpio/gpio4/value sleep 0.5 fi previous=$pin done