Shutting down your server automatically at a specific time can be useful for various reasons, such as saving energy or ensuring security after business hours. In this guide, we’ll explore how to set up automatic shutdowns using cron and systemd, and troubleshoot common issues that might arise.
Method 1: Using Crontab
Step-by-Step Guide
1. Open Crontab Configuration:
To edit the crontab for scheduling tasks, use the following command:
crontab -e
2. Add a Shutdown Command:
Add a new line to schedule the shutdown. For example, to shut down the server every day at 10 PM, add:
0 22 * * * /sbin/shutdown -h now
This cron job tells the system to execute the shutdown command at 10 PM daily.
3. Save and Exit:
Save the changes and exit the editor (usually by pressing CTRL + X, then Y to confirm, and Enter).
Method 2: Using Systemd
Step-by-Step Guide
1. Create a Systemd Service File:
Create a new service file for the shutdown task. For example, create a file named shutdown.service in /etc/systemd/system/:
sudo nano /etc/systemd/system/shutdown.service
2. Define the Service:
Add the following content to the service file:
[Unit]
Description=Shutdown the system
[Service]
Type=oneshot
ExecStart=/sbin/shutdown -h now
[Install]
WantedBy=multi-user.target
3. Create a Systemd Timer File:
Create a timer file that schedules the service. For example, create a file named shutdown.timer in /etc/systemd/system/:
sudo nano /etc/systemd/system/shutdown.timer
4. Define the Timer:
Add the following content to the timer file:
[Unit]
Description=Run shutdown service daily at 10 PM
[Timer]
OnCalendar=*-*-* 22:00:00
Persistent=true
[Install]
WantedBy=timers.target
5. Enable and Start the Timer:
Enable and start the timer with the following commands:
sudo systemctl enable shutdown.timer
sudo systemctl start shutdown.timer
Troubleshooting Tips
1. Permissions Issues
Cron jobs run with the permissions of the user who created them. If a regular user creates a cron job to shut down the server, it will fail due to insufficient permissions.
Solution:
Use sudo to ensure the shutdown command runs with the necessary privileges. Edit the crontab for the root user:
sudo crontab -e
Then add the shutdown command:
0 22 * * * /sbin/shutdown -h now
2. Incorrect Path to Shutdown Command
The cron environment might not have the same PATH variable as your shell, causing it to not find the shutdown command.
Solution:
Use the full path to the shutdown command. Verify the path using:
which shutdown
Ensure your crontab uses the full path:
0 22 * * * /sbin/shutdown -h now
3. Cron Daemon Not Running
If the cron daemon is not running, none of the scheduled jobs will be executed.
Solution:
Check if the cron service is running:
sudo systemctl status cron
If it is not running, start it:
sudo systemctl start cron
Enable it to start on boot:
sudo systemctl enable cron
4. Errors in Crontab File
If there are syntax errors or incorrect entries in the crontab file, it may prevent the cron job from running.
Solution:
Ensure there are no syntax errors in the crontab file. Edit the crontab and verify all entries are correct:
sudo crontab -e
5. Cron Logs
Reviewing cron logs can provide insights into what went wrong.
Solution:
Check the cron logs for any error messages or clues:
sudo grep CRON /var/log/syslog
Example Crontab for Root User
Here’s an example of how to set up a cron job to shut down the server daily at 10 PM, ensuring it has the correct permissions and paths:
- Edit the root crontab:
sudo crontab -e
- Add the following line:
0 22 * * * /sbin/shutdown -h now
Crontab.guru - The cron schedule expression generator*
Verifying and Testing
After setting up the crontab, you can verify it is scheduled correctly:
sudo crontab -l
Test the shutdown command manually to ensure it works as expected:
sudo /sbin/shutdown -h now
Ensure you have saved all work before testing this command.
By following these steps and troubleshooting tips, you should be able to configure your server to shut down automatically at a specified time using either crontab or systemd. If problems persist, reviewing system logs and ensuring proper permissions are the key troubleshooting steps.