The Sun introduction to Linux

Linux is considered a Unix-like operating system, primarily because no part of it was derived from the source tree of either AT&T or BSD UNIX. It originated as a project in 1991 by Linus Torvalds, then a college student at the University of Helsinki in Finland.

Linus' name is not pronounced 'Ly-nus,' but rather 'Lee-nus.' Consequently, Linux is pronounced 'Lee-nucks,' but in the U.S., it's more commonly pronounced 'Linnucks,' with a short 'i' sound. Note that 'Ly-nucks' is generally considered an incorrect pronunciation.

Linus wrote his kernel from scratch, using minix as the initial environment to develop his kernel. Minix is a free operating system used primarily as an educational tool to teach about operating systems. Linus soon expanded the kernel, posting the source code to the Internet and, before long, others began to add support for file systems and hardware.

Today, Linux has the same features as those found in other modern UNIX operating systems features such as priority scheduling, virtual memory, and multithreaded processing. It runs on 16 different architectures, including Intel, SPARC, and PowerPC.

It has support for over 30 file system types, and has drivers for over 1800 hardware components. It uses software from the open-source GNU project as its operating environment.

As mentioned in the previous section, most of the software that runs in Linux environment comes from the GNU project and is open source. Open source means that the software is distributed in the form of source code and that the source code is freely available to everyone.

However, for the software to be useful, it must be compiled into machine code. It would be very cumbersome to go about compiling all of the software required to build a Linux system.

For Redhat, Mandrake, and Sun Linux, the distribution method is rpm package files. Initially, rpm stood for Redhat Package Manager, but now uses the same pun as the GNU acronym and stands for RPM Package Manager. The rpm package format is similar in functionality to a Solaris package and uses the rpm command to install or
remove a package.

The system installation process for most Linux distributions has come a long way since the original kernel was written. My own personal experience of installing Linux for the first time was with Slackware Linux in 1994. It required that I download and create 50 floppy diskettes.

Each one of the diskettes contained a single package. In addition, the kernel needed to be compiled from source, because the stock kernel that was included to bootstrap the system only contained basic hardware support. On a machine with an Intel 486DX-33 processor, this compilation process sometimes took several hours.

Today, the installation process for most distributions is very simple and GUI driven. The basic steps for installing Linux are similar to those for installing the Solaris OE: identify the system, select the disk to install to, and choose which locales and software packages to install.

Setting the configuration for your keyboard, video card, and mouse for X Windows is required, but these tasks are fairly simple because the installation program is usually capable of probing the hardware to figure out what drivers it needs. All that is usually required from a user is to decide what resolution and color depth to run at.

In Solaris, virtually all software is documented in manual pages. The same is not true of Linux. While most of the basic UNIX commands, system calls, libraries, and system configuration files are documented in manual pages, other commands and software are documented in HOWTO and README files, GUI-based help programs, and on the Internet.

A vast number of hardware components are supported in Linux. However, support for newer hardware is not usually provided for some time. Unless the hardware vendor has written a Linux driver for their hardware, someone with programming skills must actually obtain the hardware and write a driver for it.

One of the advantages to an open-source operating environment like Linux is that when you want to get something to work, somebody has probably already written a driver for it. This includes file system drivers. For example, in Redhat 8.0, there are no less than 31 file system types supported.