Bash Script Control of GPIO Ports

The Pi's GPIO ports can be controlled from the command line (i.e. bash), python scripts, and C/C++ programs. There are 17 GPIO ports available on the Pi. Some of them have special purposes or special hardware configurations and should be avoided for normal use.

Using GPIO from bash

The following commands should be run as root (type 'sudo bash' to become root). This code sets up pin 18 to be an output, sets the pin high and then sets it low.

# Exports pin to userspace

echo "18" > /sys/class/gpio/export                  

# Sets pin 18 as an output

echo "out" > /sys/class/gpio/gpio18/direction

# Sets pin 18 to high

echo "1" > /sys/class/gpio/gpio18/value

# Sets pin 18 to low

echo "0" > /sys/class/gpio/gpio18/value 

This next snippet sets up pin 4 to be an input, then reads the value of the input.

echo "4" > /sys/class/gpio/export

echo "in" > /sys/class/gpio/gpio4/direction

cat /sys/class/gpio/gpio4/value