8 Useful Linux Shutdown Commands to Reboot or Shut Down Your Linux PC

Whether it’s for an SSH Ubuntu server or because your mouse stopped working, learning how to use Linux shutdown commands on the command line works wonders for everybody. Here we show you how to master the shutdown command to quickly shut down your PC.

Tip: Learn the differences between Shut down, hibernate or Sleep.

What’s a Shutdown Command?

On Linux, there are two ways to turn your PC off (three if pulling the plug counts):

• Pressing the shutdown button
• Shutting down via the Terminal.

While it might be a hassle trying to access Terminal first before shutting down, it’s actually pretty useful, especially for shutting down a remote Linux PC or server through SSH.

The shutdown command turns your PC off much like the shut down button on the system tray does. But it gets even better: it has options that lets you choose when to turn off, among other things.

How to Use Shutdown Commands

The format goes like this:

sudo shutdown <optional setting flag> <shutdown time> <optional message>

Like most system-level commands on Linux, you’ll need sudo to make this work. And then you can choose an option flag and other options. We’ll go through each one throughout this article.

1. Basic Shutdown Command

The shutdown command starts the shutdown process that kills all ongoing applications before powering off. This requires a time setting – you need to tell it when to shut down before it works. By adding now next to shutdown, you’re telling your PC to stop everything it’s doing and shut down immediately.

sudo shutdown now

You can also link an automatic shutdown shortcut to this command and make a DIY shutdown button. It’s a useful command for SSH servers because it’s super simple to remember. However, some Linux distros and versions might require you to add either a -h or -P flag to work.

Good to know: You can check the shutdown and reboot dates on your Linux PC easily with these tips.

2. Shutdown without Power Off

sudo shutdown -h now

or

sudo halt

There are times when it’s better to turn the computer off without taking out the power. The halt command does everything that the shutdown command does minus the final step – cutting power out from the system. This works great for when you have self-contained peripherals that take a longer time to turn off than the main computer.

However, you’re better off using the shutdown command with the -h flag. This is because shutdown allows you to set when to turn off the PC, which we’ll get into in a bit.

3. Shutdown with Power Off

sudo shutdown -P now

or

sudo poweroff

When your Linux PC or server is on a different room, having to physically press the power button would be pretty problematic. Luckily, sudo poweroff lets you automatically kill all power to the computer so your CPU would be safe from power surges and other power-related things that could break it.

Still, the best Linux shutdown command to use would be the shutdown command with the -P flag. Just remember that it needs a capitalized “P” and not a small one.

4. Shutdown after X Minutes

sudo shutdown +<minutes>

Suppose you had a process that would end in 30 minutes. Maybe you’re downloading something and you think it’ll be done at around that time. You can try replacing now with a + and how much longer you’d want it to wait in minutes before shutting down. For example: sudo shutdown +30 shuts the computer down after 30 minutes.

Remember that this does not wait for any processes to end before working, so if your task takes a little longer than it should, this Linux shutdown command will turn your PC off as soon as the countdown finishes.

5. Shutdown at a Certain Time

sudo shutdown <hour>:<minute>

If you’re like me who falls asleep on the keyboard at 3am and wakes up to a warm PC that’s been playing music from YouTube all night, you’d be wishing there was a way to turn it off after a certain time. Luckily, shutdown lets you pick a time, too.

For example, using sudo shutdown -P 2:45 shuts your Linux PC down as soon as it reaches 2:45 AM. It reads time using the 24-hour format, so you’ll need to type sudo shutdown -P 14:45 if you want to turn it off at 2:45 in the afternoon.

6. Send a Warning Message Before Shutdown

sudo shutdown <time> "<message>"

When you’re running a Linux server with multiple users connected, it will be good to send a message out to inform everyone about the shutdown. By adding something in “quotation marks”, the Linux server can relay a custom message to other users via the command line.

For automated shutdown and restart functions on servers, this message can be really important. You can add this to a script that runs upon boot. That way, your Linux server can automatically shut down for scheduled maintenance or update.

7. Basic Restart Command

sudo shutdown -r now

or

sudo reboot

By using the -r flag, you can make your PC reboot instead of powering down. You can replace now with the time to make a scheduled shutdown, which works great for automatic systems and servers with nightly updates.

Alternatively, there’s the sudo reboot command, but this one doesn’t allow you setting the time. It works the same as sudo shutdown -r now for the most part.

Tip: It is good to reboot your PC after updating your Linux kernels.

8. Forced Shutdown Commands

sudo poweroff -f

or

sudo halt -f

or

sudo shutdown -f

It’s not everyday when you get a system that just becomes unresponsive to the point that most commands won’t work. The poweroff, halt, and shutdown commands can take the -f flag to force a shut down. This is basically the electronic version of a power switch – it’ll force-kill all tasks and shut down.

Only use this for when normal shutdown and restart commands don’t work. You’re bound to lose data (and system integrity) whenever you use this.

Bonus: Cancel a Shutdown Command

sudo shutdown -c

Suppose you made a mistake and wanted to cancel a scheduled shutdown command. Neither Ctrl + C nor typing exit on the command line would stop it.

The shutdown command has a -c option which tells the system to cancel whatever time it was that you planned to shut it down.

Frequently Asked Questions

Image credit: human hand press shutdown button on virtual screen by 123RF. Screenshot by Terenz Jomar Dela Cruz

Terenz Jomar Dela Cruz

Terenz is a hobbyist roboticist trying to build the most awesome robot the world has ever seen. He could have done that already if he wasn't so busy burning through LEDs as a second hobby.