3.10 Node Assembly

4.2 Linux Kernels and Linux Distributions
Strictly speaking. Linux is just the kernel of an operating system, i.e., the master process that schedules user processes, controls devices and manages resources. In the early days, Linux was difficult to install and provided few of the tools and services that one would expect from a modern Unix-like operating system. Linux "distributions" provide the additional infrastructure that bridge the gap from a bare kernel to a fully functional operating system and user environment. Distributions provide two different and crucial services: simplified installation and a source for pre-packaged optional software components. Virtually all Linux distributions can be obtained either by downloading them from the Internet or by ordering a CD-ROM. You may wonder why you would want to pay for free software by ordering a CD. It costs money to put software on a CD, and organizations that do so need to recoup the costs involved. Several commercial Linux distributors provide technical support when you buy one of their CD-ROMs. Although support is also available separately under contract. Some vendors provide value-added features, and enhanced distributions that include commercial software such as accelerated X servers, Motif, and office productivity suites. Installation from CD-ROM is much easier than a network installation if you lack the infrastructure of a well-connected LAN and adequate temporary storage. Some of the more popular Linux distributions and their web sites are Red Hat Linux (www.redhat.com), Caldera OpenLinux (www.caldera.com), Slackware (www.slackware.org), Debian GNU/Linux (www.debian.org), S.u.S.E. Linux (www.suse.com), and Yggdrasil Plug and Play Linux(www.yggdrasil.com).
Installing a new operating system for the first time on a computer can be an intricate and highly technical procedure. Modern distributions have reduced what is essentially an extremely complex process into a series of question-and-answer screens, often with a convenient graphical user interface. Most users of computers buy operating systems pre-installed on their hard drives. The "magic" that goes into this installation procedure has been handled by the system integrator who sold the system. Today, it is possible to buy hardware systems with Linux pre-installed, but it is far more common to install Linux onto existing hardware that may already be running another operating system. Linux installation is discussed in Section 4.8.
The second major contribution made by distributions is the packaging of optional software packages. The relationships between these software packages, or applications, and the rest of the operating system environment are detailed in Figure 4.1. The popularity and success of Linux is due in large part to free software projects that are not directly affiliated with the Linux kernel development effort, but which

 



How to Build a Beowulf
How to Build a Beowulf: A Guide to the Implementation and Application of PC Clusters (Scientific and Engineering Computation)
ISBN: 026269218X
EAN: 2147483647
Year: 1999
Pages: 134

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