What command is used to shutdown a Linux system?

The command "shutdown now" is used to immediately terminate all running processes and bring the system down safely. This command initiates the shutdown sequence and can be followed by other options to specify the timing and behavior of the shutdown process.

When you run "shutdown now", the system will begin shutting down immediately, allowing any registered processes to cleanly exit and ensuring that filesystems are unmounted properly. This is important to prevent data loss or corruption. Additionally, the command can also be used with various flags and options, providing flexibility in how a shutdown is handled, such as delaying the shutdown or notifying logged-in users.

While "poweroff" and "halt" can also be used to stop the system, they do not provide the same level of gracefulness as "shutdown now". These commands typically force the system to stop operation without allowing processes to exit neatly, which can lead to issues in certain situations. "exit," on the other hand, is not a command for shutting down the system; rather, it is used to exit from a terminal session or shell. Thus, the most comprehensive and safe method for shutting down a Linux system when immediate action is needed is through the "shutdown now" command.