control reles rpi computercraft

on = "sudo sh /home/pi/on"
off = "sudo sh /home/pi/off"
local old_s = redstone.getInput("left")

while true do
  s = redstone.getInput("left")
  if s ~= old_s then
    old_s = s
    if s == true then
      http.post(
                      "http://raspberrypi/mail/mail.php",
                      "message="..textutils.urlEncode(tostring(on))
      )
    else
      http.post(
                      "http://raspberrypi/mail/mail.php",
                      "message="..textutils.urlEncode(tostring(off))
      )
    end
    redstone.setOutput("right", s)
  end
  sleep(0.5)
end