Linux with Operating System Concepts

live disk
? The 
live disk option allows you to boot directly from an optical disk (or flash drive) and thereby 
bypass the native OS. In doing so, your computer accesses all software, including the OS 
itself, off of the optical disk. Unfortunately, since the optical disk will be read-only, you 
would not be able to make permanent changes to the OS and you would have to save files 
either on a special location on your hard disk or on flash drive. Linux (and Unix) is one of 
the few operating systems that can be booted and run directly from an optical disk. MacOS 
X, some versions of Windows (but not Windows 7), and DOS are also live bootable with 
restrictions.
In this chapter, we examine Linux installation. We look at two installations, Red Hat 
Linux using the CentOS 6 distribution, and Ubuntu version 12. We make the assumption 
that you are installing in a virtual machine for simplicity. The same steps would be used 
to install on new hardware, or if you were deleting the native OS. Similar steps would be 
used in creating a dual-boot system. However, these steps are not identical and you would 
be best served to research how to set up a dual-boot system with respect to specifying disk 
partitions so that you do not damage or destroy the native operating system.
Before you begin any installation, you must understand the hardware that you are 
installing the OS onto. You should know your processor type, amount of memory, hard-
disk capacity, network card or MODEM type, whether you have USB ports, and so forth. 
You should also know the type of hard disk (IDE or SATA/SCSI) and if you have multiple 
hard disks, their types and which hard disk(s) you plan to install Linux onto.
If you are installing Linux to dual boot with an existing operating system, you should 
perform a complete backup of the current operating system and data files first. You should 
also create a DOS-bootable disk in case the master boot record becomes corrupt. If you 
make a mistake during the installation of Linux such that your native OS is damaged, 
you can then attempt to recover any damaged or lost files. While you could not reinstall 

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Linux with Operating System Concepts
the native OS from a backup, you should have or be able to obtain that operating system’s 
installation CD so that you could reinstall it if necessary and restore the remainder of your 
files from backup.
One aspect of installing Linux (at least Red Hat Linux) is that you identify a root pass-
word. To this point of the book, we have been examining Linux as a user. As we move past 
this chapter, we examine Linux from a system administration point of view.
Before we look at Linux installation, we will first examine the Linux-operating system: 
its components and what to expect from it. In Section 8.2, we also introduce the concept 
of the operating system kernel and talk about how the Linux kernel differs from those of 
other popular operating systems.
8.2 THE LINUX-OPERATING SYSTEM
We defined the operating system in Chapter 1 as software that is used to manage our com-
puter system for us. Although we do not require an operating system to use our computer, 
the operating system makes computer usage much easier. For, without the operating sys-
tem, a program that required the use of resources, such as disk access or memory move-
ment, would have to contain machine instructions that could handle such operations. In 
the earliest computers, when resources were limited to perhaps tape access and when pro-
grammers regularly moved program code in the memory using a scheme called 
memory 
overlays
,
*
adding such code to your program was common. Today, the operating system 
not only simplifies the task of the computer programmer, but it also greatly enhances the 
abilities of the user to control the computer and all of its resources.
The operating system is not a single program but a collection of programs that perform 
varying types of operations. Central to the operating system is a single program called the