port.ex

  def open_port(executable, args) do
    Port.open({:spawn_executable, executable}, [:stream, :binary, {:args, args}, :use_stdio, :stderr_to_stdout, :exit_status])
  end

  def process_port(port) do
    case collect_output(InternalData[port: port], []) do
      {status, data} -> Result[status: status, output: to_string(data)]
    end
  end

  defp collect_output(InternalData[port: port]=idata, data) do
    receive do
      {^port, {:data, new_data}} ->
        data = [data, new_data]
        collect_output(idata, data)

      {^port, {:exit_status, status}} ->
        {status, data}
    end
  end

port_example.ex

port = open_port("myscript.sh", [])
result = process_port(port)