You are reading the beginning of the lecture notes for CS 252, Introduction to Unix for Programmers, a course offered by the ODU Computer Science Department. The course is designed to introduce students to the basic Unix skills that they will need to work productively on the ODU CS Dept.'s network of Sun workstations and Linux PC's.

Whether you are enrolled in that course or not, you are welcome to peruse these notes.

You can tackle the topics in this course in different orders, depending upon your own preferences. shows how the topics that make up this course are related to one another.

An arrow from one topic to another means that you should complete the first topic before attempting the second. For example, before looking at "Program Development (via X)" you must have completed both "Program Development (via telnet)" and "Editing Files (via X)". On the other hand, you could do "Shell Games" either before or after doing "X Windows", whichever you prefer.

In addition to those seeking access to the CS Dept.'s Unix network, some people may be interested in running Linux on a home PC. Most Linux distributions will offer a terminal/command window that runs a Unix command shell called “bash” . Others who don't want to abandon Windows entirely may be interested in the Cygwin project's free port of the GNU C/C++ compilers for use on Windows 95/98/NT/2000 machines. Along with the compilers, this package provides a Unix emulation layer including the bash shell. Most of what is described in this website applies to working in bash as well.

We can actually interpret the title question in a number of different ways. Do we mean, “why does the CS department use Unix?” , or “why is this course about Unix?” , or “why was unix invented?” , or even “why does Unix behave the way that it does?”

It's actually the last of these interpretations that I want to address, although understanding the answer to that question will go long ways towards explaining why the CS department uses Unix in most of its courses and, therefore, the very reason for the existence of this course.

I think that, to really understand a number of the fundamental behaviors of Unix, it helps to consider how Unix is different from what is probably a much more familiar operating system to most of you, Microsoft Windows. Furthermore, to understand the differences between these operating systems, you need to look at the history of computer hardware and system software evolution in effect at the time when each of these operating systems was designed. In particular, I want to focus on three ideas: evolution of CPU's and process support, evolution in display technology, and evolution in network and technology.