Raspberry Pi + Ruby (WiringPi) + LED

blink.rb

require 'wiringpi'

# run: rvmsudo ruby blink.rb

ledPin = 5

io = WiringPi::GPIO.new
io.mode(ledPin, OUTPUT)
loop do
        io.write(ledPin, HIGH)
        sleep(0.5)
        io.write(ledPin, LOW)
        sleep(0.5)
end