import?grp
import?subprocess

def?ensure_gpiogroup（）:
????try:
????????grp.getgrnam（‘gpio‘）
????except?KeyError:
????????print（‘GPIO?group?does?not?exist?-?creating...‘）
????????subprocess.call（[‘groupadd‘?‘-f‘?‘-r‘?‘gpio‘]）
????????subprocess.call（[‘adduser‘?‘pi‘?‘gpio‘]）
????????#?in?future?also?for?groups:
????????#???spi
????????#???i2c
????????add_udev_rules（）

def?add_udev_rules（）:
????with?open（‘/etc/udev/rules.d/99-gpio.rules‘‘w‘）?as?f:
????????f.write（“““SUBSYSTEM==“bcm2835-gpiomem“?KERNEL==“gpiomem“?GROUP=“gpio“?MODE=“0660“
SUBSYSTEM==“gpio“?KERNEL==“gpiochip*“?ACTION==“add“?PROGRAM=“/bin/sh?-c?‘chown?root:gpio?/sys/class/gpio/export?/sys/class/gpio/unexport?;?chmod?220?/sys/class/gpio/export?/sys/class/gpio/unexport‘“
SUBSYSTEM==“gpio“?KERNEL==“gpio*“?ACTION==“add“?PROGRAM=“/bin/sh?-c?‘chown?root:gpio?/sys%p/active_low?/sys%p/direction?/sys%p/edge?/sys%p/value?;?chmod?660?/sys%p/active_low?/sys%p/direction?/sys%p/edge?/sys%p/value‘“
“““）

if?__name__?==?‘__main__‘:
????ensure_gpiogroup（）