Halt Command (with examples)
- Linux
- November 5, 2023
Introduction
The halt command is used to halt the system by shutting it down in an orderly manner. It is typically utilized when you want to turn off the system or reboot it. In this article, we will explore various use cases of the halt command and provide examples for each.
1. Halt the system
The first use case is to simply halt the system. This can be done by executing the following command:
halt
Motivation: This use case is useful when you want to shut down the system properly without rebooting or taking any other action.
Example Output: The system will be halted, and all processes will be stopped one by one until the shutdown process is complete.
2. Power off the system
To power off the system using the halt command, you can add the --poweroff argument as shown below:
halt --poweroff
Motivation: This use case is beneficial when you want to shut down the system and turn off the power completely.
Example Output: The system will be halted, and then the power will be turned off.
3. Reboot the system
To reboot the system using the halt command, you can use the --reboot argument:
halt --reboot
Motivation: This use case is handy when you want to shut down the system and restart it immediately.
Example Output: The system will be halted, and then it will be restarted.
4. Halt immediately without contacting the system manager
If you want to halt the system forcefully without contacting the system manager, you can use the --force argument twice:
halt --force --force
Motivation: This use case is useful when you want to halt the system immediately, ignoring any ongoing processes or connections that the system manager might be handling.
Example Output: The system will be halted instantly without waiting for ongoing processes to finish.
5. Write the wtmp shutdown entry without halting the system
If you only need to write the wtmp shutdown entry without actually halting the system, you can use the --wtmp-only argument:
halt --wtmp-only
Motivation: This use case can be handy when you want to record a shutdown event in the wtmp file without actually shutting down the system.
Example Output: The wtmp file will be updated with the shutdown entry, but the system will continue to run as usual.
Conclusion
In this article, we explored different use cases of the halt command and provided code examples for each. Whether you want to halt the system, power it off, reboot it, force a halt without contacting the system manager, or only update the wtmp file, the halt command offers various options to suit your needs.
