InformIT: Red Hat Linux 7 Unleashed

The Boot Process

In Chapter 2, "Installation of Your Red Hat System," you learned how to install Linux, and in Chapter 3, "LILO and Other Boot Managers," you found out how to install and use different loaders for different computers. A number of ways exist to start Linux with different computers, and there are different ways to load the Linux kernel. Intel Linux users will most likely use LILO, LOADLIN, SYSLINUX, BOOTLIN, or commercial alternatives such as System Commander or BootMagic. SPARC users will use SILO, and Alpha users will probably use MILO. You'll find the basic steps outlined in your Red Hat Linux Users Guide (if you purchased the "Official" distribution) or through Red Hat at http://www.redhat.com/support/manuals.

I'm assuming most readers will install Red Hat Linux/Intel, so here's a little background on how the Red Hat Linux startup process is different from that of other UNIX operating systems, such as BSD.

PCs start by looking at the first sector of the first cylinder of the boot drive and then trying to load and execute code found there (which is one way LILO can work, as explained in Chapter 3). This is also the case with other (but not all) hardware systems and versions of UNIX. You should be able to set the order in which your PC looks for the boot drive, usually through a BIOS change in a setup menu that you can invoke when you first turn on your machine (usually accomplished by pressing a Function key, such as F1 or F2, or a combination of keys, such as Fn and Esc on various laptops). Setting the boot order can be handy if you never use a boot floppy disk. For example, laptop users with an external floppy drive can speed up the boot process by directing the computer to look first at the internal hard drive or CD-ROM.

You can also start Linux over a network and run a diskless Linux box. For more information on how to do this, see Robert Nemkin's Diskless Linux Mini HOWTO, available at http://www.linuxdoc.org. Although Linux shares many similar traits with both System V and BSD UNIX, in the case of booting and starting the system, Linux is closer to the former. This means Linux uses the init command and a similar directory structure of associated scripts to start running the system and loading processes.

According to the Red Hat folks, this approach is becoming the standard in the Linux world because it is "easier to use and more powerful and flexible." Latest estimates, based on distribution sales, point to nearly 60% of Linux users using a Red Hat or Red Hat-based Linux system. Indeed, other distributions, such as Caldera's OpenLinux, use a similar initialization scheme (albeit with different naming conventions for scripts).

You'll also see why boot configuration is even easier for Red Hat Linux users when you learn about the linuxconf client later in this chapter in the section "linuxconf and Managing Your Services."

The Initialization Process and Startup Scripts | Next Section

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