rpi-config.install

function maybe_add_group {
  getent group "$1" >/dev/null 2>&1 || groupadd -r "$1"
}

function post_install {
  maybe_add_group gpio
  maybe_add_group i2c
  maybe_add_group spi

  echo "Make sure to configure /etc/wpa_supplicant/wpa_supplicant-wlan0.conf"
}