rock64 power led heartbeat indicator

rock64-power-led-heartbeat.sh

#!/bin/bash

#if a gpio group exists, doing this at startup allows any group member to control leds
#sudo chgrp gpio /sys/class/leds/{diy,work}-led/brightness
#sudo chmod g+w /sys/class/leds/{diy,work}-led/brightness

LED_GPIO="/sys/class/leds/power-led"
LED_ON=255
LED_OFF=0

RequireRoot() {
	if [ "$(id -u)" != "0" ]; then
		echo "This function requires root privleges - run as root or through sudo. Exiting" >&2
		exit 1
	fi
} # RequireRoot

ParseOptions() {
	while getopts 'hHsSiI' c ; do
	case ${c} in
		s|S)
			RequireRoot
			SetupGPIOs
			exit 0
			;;

		i|I)
			RequireRoot
			InstallToRcLocal
			exit 0
			;;
		h|H)
			DisplayUsage
			exit 0
			;;
	esac
	done

} # ParseOptions

Cleanup()
{
        exit 0
} # Cleanup

SetupGPIOs()
{
	[ $SUDO_USER ] && user=$SUDO_USER || user=`whoami`
    
    echo "Ensuring 'gpio' group exists..."
	getent group gpio >/dev/null 2>&1 || groupadd gpio

	echo "Ensuring '$user' is in gpio group..."
	usermod -aG gpio $user

	echo "Setting necessary group permissions..."
	chgrp gpio /sys/class/leds/{standby,power}-led/brightness
	chmod g+w /sys/class/leds/{standby,power}-led/brightness
} # SetupGPIOs

InstallToRcLocal() {
	local SCRIPT=`realpath $0`
	cat >/etc/rc.local << EOL
#!/bin/bash
$SCRIPT -s
$SCRIPT &
exit 0
EOL

	chmod +x /etc/rc.local

	echo "Reboot to see the changes!"
} # InstallToRcLocal


DisplayUsage()
{
	echo "TBC"
}

Main()
{
	ParseOptions "$@"

	#exit nicely if Ctrl-C pressed, SIGTERM, etc sent
	trap Cleanup SIGHUP SIGINT SIGTERM

	#make sure led is off, and delay for asthetics
	echo ${LED_OFF} > "${LED_GPIO}/brightness" #off
	sleep 0.5s

	#main loop
	while true
	do
        	echo ${LED_ON}  > "${LED_GPIO}/brightness" #on
	        sleep 0.1s
	        echo ${LED_OFF} > "${LED_GPIO}/brightness" #off
	        sleep 0.1s
	        echo ${LED_ON}  > "${LED_GPIO}/brightness" #on
	        sleep 0.1s
	        echo ${LED_OFF} > "${LED_GPIO}/brightness" #off
	        sleep 9.7s
	done

	exit 0
} # Main

Main $@