#!/bin/bash

echo "4" > /sys/class/gpio/export
echo "in" > /sys/class/gpio/gpio4/direction

previous=$(cat /sys/class/gpio/gpio4/value)

while true
do
  pin=$(cat /sys/class/gpio/gpio4/value)

  if [ $pin -ne $previous ]
  then
    if [ $pin -lt $previous ]
    then
      echo "$(date '+%d.%m.%Y %H:%M') ein" >> /var/www/log.txt
    else
      echo "$(date '+%d.%m.%Y %H:%M') aus" >> /var/www/log.txt
    fi
  fi

  previous=$pin
  sleep 0.5
done