gpio-low

#!/bin/bash

############################################################################################################
#
#  RASPBERRY PI GPIO TO LOW CONTROL THROUGH THE TERMINAL
#
#    This script takes the pin numbers to change as arguments
#    Sets them to low
#
############################################################################################################

# THERES A BUG WITH THE RASPBERRY WHERE YOU NEED TO BE LOGGED AS ROOT TO BE ABLE TO CHANGE THE PINS STATES
# WHICH IN TURN MEANS THAT WE NEED TO USE "sudo -i <<EOF"
# THAT MAKES THE VARIABLE EXPANSION ACT IN SOME UNEXPECTED WAYS AND INCONVENIENT WORKAROUNDS HAD TO ME MADE


# Loop through the arguments
for pin; do

	# Need to run this as root user. Using sudo won't work
	sudo -i <<-EOF	# need to do -EOF instead of EOF to be able to use indentation

	# Check if the pin is exported, otherwise no need to do anything
	# Using a trailing slash on the path makes sure that we are checking for a directory
	if [[ -d "/sys/class/gpio/gpio$pin/" ]]; then
		# Set the pin LOW
		echo 0 > "/sys/class/gpio/gpio$pin/value"

		# Would unexport the pin but then you can't export it and set it high again
		# Probably a bug
	fi

	# Info message
	echo "Set pin $pin LOW"

	# Close EOF
	EOF

done