local IDENTIFIER = user
local DELAY_TIME = 60

local function main_loop()
  while true do
    local x, y, z = gps.locate()
    peripheral.call("back", "transmit", 1500, 1500, {identifier = IDENTIFIER, x, y, z})
    sleep(DELAY_TIME)
  end
end

local function _shell()
  shell.run("shell")
end

parallel.waitForAny(main_loop, _shell)