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How to Automatically Check and Restart a VirtualBox VM on Ubuntu

Introduction​

Have you ever had a critical service running inside a VirtualBox virtual machine (VM), like a web server, database, or development environment, that needs to be online 24/7? If so, you might have worried about what would happen if the VM shuts down unexpectedly due to a server reboot or an error.

This guide is here to help you solve that exact problem. We'll walk you through creating a simple automated solution on Ubuntu that regularly checks if your VirtualBox VM is running and, if it's not, automatically starts it back up. By the end of this tutorial, you'll have a reliable setup that ensures your VM is always available when you need it.

The Scripts​

We'll use two simple shell scripts to accomplish this: one to check the VM status and another to set up a scheduled task.

1. The Status Checker Script (check_vm_status.sh)​

This script checks if your specified VM is running. If it finds that the VM is not running, it will start it. It also keeps a log file so you can see when it has been run and what it did.

Here is the code. You will need to change the VM_NAME variable to the name of your virtual machine.

#!/bin/bash

# VM name
VM_NAME="docker-host-1"

# Log file
LOG_FILE="vm_check.log"

# Timestamp
TIMESTAMP=$(date)

# Check if the VM is running
if VBoxManage showvminfo "$VM_NAME" | grep -q "running (since"; then
    echo "--------------------------------" >> "$LOG_FILE"
    echo "Running check at $TIMESTAMP" >> "$LOG_FILE"
    echo "VM is already running." >> "$LOG_FILE"
else
    echo "--------------------------------" >> "$LOG_FILE"
    echo "Running check at $TIMESTAMP" >> "$LOG_FILE"
    echo "VM is not running. Starting it now..." >> "$LOG_FILE"
    VBoxManage startvm "$VM_NAME" --type headless >> "$LOG_FILE" 2>&1
    echo "VM started." >> "$LOG_FILE"
fi

2. The Cron Setup Script (setup_cron.sh)​

This script creates a "cron job," which is a scheduled task that runs automatically at a specified time. This cron job will execute our check_vm_status.sh script every day at 4:00 AM.

Important: You will need to edit this script to provide the correct path to your check_vm_status.sh script.

#!/bin/bash

CRON_JOB="0 4 * * * /path/to/your/check_vm_status.sh"

# Add the cron job
(crontab -l 2>/dev/null; echo "$CRON_JOB") | crontab -

echo "Cron job added successfully:"
echo "$CRON_JOB"

Setup Instructions​

Now, let's put it all together.

Step 1: Save the Scripts​

Save the two scripts above as check_vm_status.sh and setup_cron.sh in a directory of your choice on your Ubuntu machine.

Step 2: Make the Scripts Executable​

Open a terminal and navigate to the directory where you saved the files. Run the following command to make the scripts executable:

chmod +x check_vm_status.sh
chmod +x setup_cron.sh

Step 3: Update the Path in setup_cron.sh​

Before you run the setup script, you need to edit it to include the correct path to check_vm_status.sh.

  1. Get the full path to your script by running the following command in the directory where you saved the files: 
    readlink -f check_vm_status.sh
  2. Copy the output of that command.
  3. Open setup_cron.sh in a text editor and paste the copied path in place of /path/to/your/check_vm_status.sh.

Step 4: Run the Cron Setup Script​

Now you are ready to set up the cron job. Run the following command:

./setup_cron.sh

You should see a confirmation message that the cron job was added successfully.

Verifying the Setup​

Checking the Cron Job​

You can verify that the cron job was added by running the following command:

crontab -l

This will list all the active cron jobs for the current user. You should see the line that was added by the setup script.

Checking the Log File​

The check_vm_status.sh script will create a vm_check.log file in the same directory. You can check this file to see the script's activity.

cat vm_check.log

You should see output similar to this:

--------------------------------
Running check at Tue  4 Nov 21:13:19 GMT 2025
VM is already running.

Conclusion​

Congratulations! You now have an automated system that ensures your VirtualBox VM is always running. This simple solution provides peace of mind, knowing that your important services will automatically restart if they ever go down.

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