# 8.3. Environment Variables

All utilities provided by GPIO Zero accept the following environment variables:

GPIOZERO_PIN_FACTORY

  The library to use when communicating with the GPIO pins. Defaults to attempting to load lgpio, then RPi.GPIO, then pigpio, and finally uses a native Python implementation. Valid values include “lgpio”, “rpigpio”, “pigpio”, “native”, and “mock”. The latter is most useful on non-Pi platforms as it emulates a Raspberry Pi model 3B (by default).

PIGPIO_ADDR

  The hostname of the Raspberry Pi the pigpio library should attempt to connect to (if the pigpio pin factory is being used). Defaults to `localhost`.

PIGPIO_PORT

  The port number the pigpio library should attempt to connect to (if the pigpio pin factory is being used). Defaults to `8888`.