Shell Script for door monitor

doorStatus.sh

# ------------------------------------------------------------------------------------------ #
# This script is used to monitor the status of a door with a Raspberry Pi 3 Mobel B          #
# and send an email when the door is opened or closed                                        #
# ------------------------------------------------------------------------------------------ #
#!/bin/bash
echo "4" > /sys/class/gpio/export
echo "in" > /sys/class/gpio/gpio4/direction

# create an infinite loop inside wwhich operations will be done
# to continuously check for door status and send notifications
while true; 
do 

    trap 'echo "4" > /sys/class/gpio/unexport' 0

    # get the state value of the pin on the raspberry
    stat=`cat /sys/class/gpio/gpio4/value`

    while [$stat = "1"]
    do
        # get date and time
        date=`date +%d-%m-%Y`
        time=`date '+%H:%M'`

        # display door status
        echo "Door opened at $time on $date"
        # send an email notification
        echo "Hi, Door opened at $time on $date" | mail -s "Door Opened" example@gmail.com

        # save notificationn in a daily log file 
        echo "Door was opened at $time on $date" >> log$date.txt

            # wait for the door to be closed again
            while [$stat = "1"]
            do
                stat=`cat /sys/class/gpio/gpio4/value`
                
                # add a waiting time
                sleep 0.09
            done 
        
        # for when the door is closed 
        # get date and time
        date=`date +%d-%m-%Y`
        time=`date '+%H:%M'`

        # display door status
        echo "Door was closed at $time on $date"
        # send an email notification
        echo "Hi, Door closed at $time on $date" | mail -s "Door Closed" example@gmail.com

        # save notificationn in a daily log file 
        echo "Door was closed at $time on $date" >> log$date.txt
    done
    
    # add a waiting time reduce the the processor use by over 90%
    sleep 0.09

done

exit 0
# ------------------------------------------------------------------------------------------ #