The most elaborate light switch in the world

By combining the two little projects earlier, we can now create a system that will do something useful when the pushbutton switch is pushed—for example, switching on the LED that we also have connected. Granted, we could just connect the LED directly to the switch and a battery, but not only would that be boring, it would defeat the point of what we're trying to do, which is programmatically sensing and controlling things.

Here's the breadboard layout for our elaborate light switch:

And here's the circuit diagram:

The illuminating script

Our full Bash script for our elaborate light switch is demonstrated next. This will loop endlessly, detecting the state of the switch GPIO pin, and will turn on the LED GPIO pin when the switch is pushed.

The code listing for light-switch.sh is as follows:

#!/bin/bash

#set up the LED GPIO pin
sudo echo 17 > /sys/class/gpio/export
sudo echo out > /sys/class/gpio/gpio17/direction

#set up...