Lock Apple Mac screen when bluetooth device, such as a phone, goes out of range

bluetooth-screen-lock

# MAC=xx-xx-xx-xx-xx-xx
MAX_IDLE=10
while true ; do
	idle=$(/usr/sbin/ioreg -c IOHIDSystem | /usr/bin/awk '/HIDIdleTime/ {print int($NF/1000000000); exit}')
	if (( idle < MAX_IDLE )) ; then
		sleep $(( MAX_IDLE - idle + 1 ))
        else
		blueutil --inquiry 4 | grep -E "$MAC" || {
			echo "Locking screen..."
			pmset displaysleepnow
			sleep 2m
		}
		sleep 1
        fi
done