Shutdown EC2 instance after timeout if no one is connected via ssh

stop-if-inactive.sh

#!/bin/bash

# based on AWS Cloud9
# shutdown ec2 if no ssh connections after 1/2 hour
#  Add to cron to run every minute
#  User needs sudo permission to run 'shutdown'
#

set -euo pipefail

SHUTDOWN_TIMEOUT=30     # minutes
if ! [[ $SHUTDOWN_TIMEOUT =~ ^[0-9]*$ ]]; then
    echo "shutdown timeout is invalid"
    exit 1
fi

is_shutting_down() {
    pgrep shutdown >/dev/null
}
is_ssh_connected() {
        netstat | grep ssh | grep ESTABLISHED >> /dev/null;
}

if is_shutting_down; then
    if is_ssh_connected; then
        sudo shutdown -c
    fi
else
    if ! is_ssh_connected; then
        sudo shutdown -h $SHUTDOWN_TIMEOUT
    fi
fi