This command makes a program run as root (the system administrator). This command is only allowed to be used by few users. Such users are called sudoers. You can modify the sudoers using
This command makes the system shutdown. You can use the following command to shutdown the system immediately
shutdown -h now
The alternative command to shutdown immediately is: "halt"
Restart the system
To restart the system, you can use "reboot" command.
Please note that above commands (shutdown, halt, reboot) can only be run as root.