PlusberryPi Power

pwrbutton.sh

#!/bin/bash
# monitor GPIO pin 21 for shutdown signal
# export GPIO pin 21 and set to input with pull-up

echo "21" > /sys/class/gpio/export
echo "in" > /sys/class/gpio/gpio21/direction

# wait for pin to go low
while [ true ]; do
  if [ "$(cat /sys/class/gpio/gpio21/value)" == '0' ]; then
    echo "Raspberry Pi Shutting Down!"
    halt &
    exit 0
  fi
  sleep 1
done