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GNU/Linux Overview

Introductions

Teachers introduce themselves, ask the class to introduce themselves.

Why Do You Want To Learn About GNU/Linux?

Ask around, get feedback on why are people here, and what would they like to learn.

Course Outline

  1. Introduction to GNU/Linux (this class!): TobyCabot March 5, 2003
  2. Desktop Apps and Tools / Shell and File System: Forrest Sutton, TobyCabot & Ed Frankenberry (EdF) March 12, 2003
  3. Installation of Linux: Forrest Sutton March 19, 2003
  4. Web Servers: TobyCabot March 26, 2003
  5. Support and Documentation: Ed Frankenberry (EdF) April 2, 2003
  6. To be determined April 9, 2003

What is GNU/Linux?

Linux is a "kernel" which is a small program that's the heart of the computer operating system. Let's quote from the source code:

WHAT IS LINUX?

  Linux is a Unix clone written from scratch by Linus Torvalds with
  assistance from a loosely-knit team of hackers across the Net.
  It aims towards POSIX compliance.

  It has all the features you would expect in a modern fully-fledged
  Unix, including true multitasking, virtual memory, shared libraries,
  demand loading, shared copy-on-write executables, proper memory
  management and TCP/IP networking.

GNU/Linux is an operating system that's built from the Linux kernel and many other programs. GNU/Linux is different from many other operating systems because you can get the source code and build it, learn from it, improve it, or get into a lot of trouble.

GNU/Linux "distributions" package GNU/Linux and other programs on CDROM and make it easy (at least easier) to install and run. There are many distributions, but a few important ones are Debian, Mandrake, and Red Hat. Red Hat is the most popular, Mandrake is good for desktop machines, and Debian is very high-quality but is considered more difficult to install.

What is Unix?

Unix is an operating system that was developed at Bell Laboratories in the early 1970's. First portable OS. It's a multi-user operating system, so many people can use it at the same time (it's suitable for use as a server).

For many years Unix ran only on expensive minicomputers. Even today, large Unix systems from companies like Sun and HP can cost over a million dollars.

Unix servers are used in many companies for "mission critical" tasks such as running large databases, accounting systems, billing systems, etc.

Unix History

Back in the early 1970's AT&T was the telephone monopoly in the US. The research arm, called "Bell Labs", performed basic and applied research. Not allowed to sell SW but were paid to do research. Long history of many innovations including invention of information theory, communications satellites, transistor, etc.

Dennis Ritchie, Ken Thompson.

UC Berkeley, the Berkeley Software Distribution (BSD).

The Unix code written by AT&T (eventually called System V or "SysV") was eventually sold several times and is now owned by a company called SCO.

Free Software/Open Source History

Richard Stallman, GNU Project, GPL, Free Software Foundation.

The GPL license (also called Copyleft) was designed to ensure that users would always have four freedoms (quoting the GNU web site):

Other licenses are available, many are "Open Source". BSD, Apache, Artistic, Public Domain.

Other Free Software/Open Source success stories:

"The Cathedral and the Bazaar"

GNU/Linux History

Linus Torvalds (a Swedish-speaking Finn) started in 1990/1991 while he was a student in Helsinki. Linux Kernel Mailing List. Distros: SLS, Slackware, Red Hat, Mandrake, Debian. Reached 1.0 milestone in 1994, now at 2.4 (soon 2.6).

Development happens on multiple "branches" at the same time. Odd-numbered branches (2.1, 2.3, 2.5 etc) are for developers, when they're ready for the rest of us they're renumbered as even-numbered branches (2.2, 2.4, someday 2.6).

What does GNU/Linux look like? (Show a command-line login)

X Windows. (Show KDE)

GUI environments: GNOME, KDE.

What Makes Unix Special?

Elegant, consistent, software tools that can be used alone or in combination.

From the preface of the book The UNIX Programming Environment by Brian W. Kernighan and Rob Pike, published in 1984 by Prentice Hall, Inc:

Even though the UNIX system introduces a number of innovative programs and techniques, no single program or idea makes it work well. Instead, what makes it effective is an approach to programming, a philosophy of using the computer. Although that philosophy can't be written down in a single sentence, at its heart is the idea that the power of a system comes more from the relationships among programs than from the programs themselves. Many UNIX programs do quite trivial tasks in isolation, but, combined with other programs, become general and useful tools. Do one thing and do it well.

Build your own tools, assemble small tools into larger ones; pipes and scripts; everything's a file. Teach people to fish.

What Makes Linux Special?

Unix power on inexpensive, commodity hardware. Learn about computers. Participate in improving it. Have fun!

Last but not least, Linux has a fun mascot: Tux the penguin.

What Can I Do With GNU/Linux?

Does GNU/Linux Have Any Weaknesses?

Where Do I Go For More Info?

Links

-- TobyCabot and EdF - 27 Feb 2003

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