Alex Ruben
How To Automate Nightly Reboots on Ubuntu with Crontab
Sometimes, your Ubuntu machines can get pretty sluggish over time, especially if they’re always on or running critical services. Regular reboots can help clear out temp files, refresh memory, or just fix sneaky glitches that crop up. Setting up a nightly reboot with crontab isn’t super complicated, but it’s one of those things you might not think of until your server’s behaving weirdly. This guide walks through how to automate it, so your system reboots at a specific hour every night, hopefully making things run smoother without manual intervention.
How to Fix Nightly Reboots with a Crontab Entry
Make sure you have the right permissions and environment
Before diving in, double-check your permissions. Crontab can be a little tricky—if you’re trying to schedule a system reboot, you probably need to be root, so use sudo crontab -e instead of just crontab -e. Also, confirming that your system’s clock is correct is crucial — otherwise, the reboots might happen at weird hours or not at all.
Method 1: Editing the root crontab for scheduled reboots
This is the most common way—it tells your system to reboot without any manual prompts every night. On some setups, this fails if you forget to use sudo or if your PATH isn’t set right, so be aware. Here’s how to do it:
- Open terminal (press Ctrl + Alt + T), then enter
sudo crontab -e. This opens the root’s cron jobs. - Once inside, go down to the bottom and add this line:
0 3 * * * /sbin/shutdown -r now0 2 * * * would reboot at 2AM.Why it helps: It basically tells your system, “Hey, at 3AM every night, reboot now.” The /sbin/shutdown -r now command forces an immediate restart. On some machines, the first attempt might not work because of permission issues or environment paths, but if you run sudo crontab -l afterward, you should see your schedule listed.
Method 2: Using an /etc/cron.d/ custom file
If you want a bit more control and robust logging, creating a custom cron file in /etc/cron.d/ can be a smarter choice. Just make a file like nightly-reboot and put your schedule there:
sudo nano /etc/cron.d/nightly-rebootInside, add:
0 3 * * * root /sbin/shutdown -r nowThis method helps keep your main crontab clean, and it’s nice if you have multiple complex scheduled tasks. Again, verify your permissions and ensure /sbin/shutdown exists and is executable.
Extra tips & troubleshooting
- Double-check your system time with
timedatectl, make sure it’s accurate; otherwise, reboots might happen at odd hours or not align with your expectations. - If you modify your crontab or cron files, make sure those changes save properly. It’s easy to miss, especially if you’re editing with a less familiar editor.
- In some cases, your shutdown command might need absolute paths or specific flags depending on your setup. If
/sbin/shutdown -r nowdoesn’t work, try/bin/systemctl reboot. - Check cron logs if things aren’t working: sudo tail -f /var/log/syslog or /var/log/cron.log (depends on distro). You’ll see any errors or skipped jobs there.
Wrap-up
Once all that’s done, your system should automatically reboot every night at your set time, which can be a real time-saver. The key is making sure you’re editing the right cron file with the proper permissions and verifying your schedule is in place. Sometimes, it’s just a matter of patience and a few tweaks, especially if your system clocks are off or cron isn’t running properly.
Summary
- Use
sudo crontab -eor create a file in /etc/cron.d/ for more control. - Schedule
/sbin/shutdown -r nowat your preferred time. - Check that the system time is correct and cron service is active.
- Verify your cron jobs with
crontab -lor through log files.
Fingers crossed this helps
Getting automated reboots set up can be a bit finicky at first, but once you get it working, it’s a weird satisfying feeling knowing your machine’s maintenance is handled overnight. Not sure why it works, but on some setups, a reboot seemed to hang or not trigger, so keep an eye on your logs and make sure cron’s running properly. Good luck, and hope this gets one more thing off your plate!