Shutdown Idle EC2 instances after 5 minutes of no SSH activity

idle_shutdown.sh

#crontab entry - replace your_user with your actual user name
#*/10 * * * * /home/your_user/idle_shutdown.sh > shutdown_logs.txt

#check for established SSH connections
SSH_CONNS=`netstat | grep ssh | grep ESTABLISHED`
#If None
if [ -z "$SSH_CONNS" ]
then
    #wait 5 minutes and check again
    echo "No SSH Connections. Checking again in 5 minutes"
    sleep 5m
    SSH_CONNS2=`netstat | grep ssh | grep ESTABLISHED`
    #If still no SSH connections
    if [ -z "$SSH_CONNS2" ]
    then
        #kill instance
        /sbin/shutdown -h now
    else
        echo "Active SSH conncections established during waiting period" 
    fi
else
     echo "Active SSH conncections"
fi