Learn Linux, 101: Runlevels, shutdown, and reboot

Learn Linux, 101: Runlevels, shutdown, and reboot: "Learn to shut down or reboot your Linux system, warn users that the system is going down, and switch to a more or less restrictive runlevel. You can use the material in this article to study for the LPI 101 exam for Linux system administrator certification, or just to learn about shutting down, rebooting, and changing runlevels."