Introduction

All Linux users and system administrators need to know how to shut down the entire system safely. There are several options to do so, including scheduling a shutdown at a specific time, shutting down immediately, broadcasting a unique message, and so on.

In this tutorial, learn how to use the Linux shutdown command with examples.

shutdown Command Syntax

Before going into specific ways to shut down your Linux system, you should understand the basic syntax of the shutdown command:

shutdown [options] [time] [message]

• [options] define whether you want to halt, power-off, or reboot the machine.
• [time] specifies when you want the shutdown to perform.
• [message] adds a message that announces the shutdown.

How to Use the shutdown Command

To use the shutdown command on Linux systems, a  root user or a user with sudo privileges is required.

If you use the command without additional arguments, running sudo shutdown in a terminal window executes the shutdown in 60 seconds.

In the image below, see the output received after running the shutdown command.

Shutdown With All Parameters

To view all parameters when shutting down the Linux system, use the following command:

sudo shutdown --help

The output displays a list of shutdown parameters, as well as a description for each.

How to Shut Down the System at a Specific Time

To schedule a shutdown, add the [time] argument and specify when you want it to take place. There are two ways to shut down the system at a specific time – using the absolute or relative time format.

The absolute time follows the format hh:mm and allows you to schedule a shutdown at a specified time. The command follows the syntax:

sudo shutdown hh:mm

For example, to require a shutdown at 7 AM in the morning, the command is:

sudo shutdown 07:00

Alternatively, use the relative format (+m) and schedule a shutdown in a defined number of minutes from the time you run the command. In that case, the command syntax is:

sudo shutdown +m

To shut down the system in 20 minutes, run:

sudo shutdown +20

How to Shut Down the System Immediately

As previously mentioned, running the shutdown command without any arguments prompts the system to shut down a minute after running the command. However, if you require an immediate shutdown, use:

sudo shutdown now

Another option would be to schedule a shutdown using the relative time format with the value 0, as in the command below:

sudo shutdown +0

How to Broadcast a Custom Message

Once you schedule a system shutdown, all users within the system receive a message notifying them of the shutdown. To add a custom message to the shutdown notification to inform the users what is about to take place.

You can add a [message] only if the command also includes the [time] attribute:

sudo shutdown [time] "[message]"

For instance, to shut down the system in 20 minutes and broadcast the message System Upgrade, run:

sudo shutdown +20 "System Upgrade"

How to Cancel a Scheduled Shutdown

To cancel a scheduled shutdown, use the command:

sudo shutdown -c

You can also add a message to notify users that the shutdown is canceled. To do so, add the [message] option (within quotations) to the command above. For example:

sudo shutdown -c "Canceling System Upgrade"

Conclusion

This article includes all the basic shutdown commands every Linux user should know. Utilizing this command is a safe way to shut down your system. Also, it is a useful method of informing all users about scheduled shutdowns.

shutdown [OPTIONS] TIME [MESSAGE]