Chapter 14. Boot, Initialization, Shutdown, and Runlevels (Topic 1.106)

Even the most inexpensive PC has a fairly complex series of steps to execute on its way from idle hardware to productive system. When a system is powered on, a computer's electronics are in a random state and must be reset to a known condition. After this occurs, the CPU in the system begins processing instructions at a specific, hardcoded memory location in ROM. For PCs, the ROM is usually called the BIOS. The startup instructions stored in the BIOS perform basic initialization chores to discover and configure peripheral hardware. When the system is initialized and ready, it begins looking in known locations for an operating system (or operating system loader software). This could be stored on fixed or removable disk media or even placed in memory during initialization. Once an operating system is launched, it begins an initialization sequence of its own.

This chapter covers the latter portions of the boot process, from the point when the BIOS looks for an operating system, as required for Exam 102. (The BIOS is covered in Chapter 3.) This Topic has two Objectives:

Objective 1: Boot the System

Candidates should be able to understand the system booting process. This includes giving commands to the boot loader and giving options to the kernel at boot time and checking events in the log files. Weight: 3.

Objective 2: Change Runlevels and Shut Down or Reboot System

This Objective states that a candidate should be able to manage the runlevel of the system. This includes changing the system to single-user mode, shutting it down, or rebooting it. Candidates must also be able to alert users and terminate system processes when changing system runlevels. Weight: 3.