1. Introduction

1.1 About This Document

Copyright (c) 1997 by

Russell C. Bjork,
Professor of Computer Science,
Gordon College,
Wenham MA 01984.

This document is based on An Introduction to Ultrix for VMS Users copyright (c) 1996 by Russell C. Bjork, which in turn was based on An Introduction to Berkeley Unix 4.3 for VMS Users version 1.4, copyright (c) 1996, 1994, 1992, 1990, 1987 by Russell C. Bjork.

The conversion of the contents to IRIX and the format to HTML was done by Jonathan R. Senning in the fall of 1997.

1.2 About Unix and IRIX

IRIX is a version of the Unix operating system developed and distributed by Silicon Graphics (SGI) for use on its various computer systems.

IRIX is derived from four main sources: AT&T, Berkeley, MIPS Computer Systems, and Sun Microsystems.

This document is intended to serve as an introduction to IRIX for a person who is already familiar with the VMS operating system normally used on VAXes. For this reason, it concentrates on the major features common to both operating systems, and on the differences related to those features. For a full introduction to the distinctive features of Unix (of which there are many), the user must consult the appropriate manuals (online in the form of the man command and the help available from the desktop menu).

While SGI machines make extensive use of a graphical user interface (GUI), access to many system and user commands is through a command-line interface, much as on a VMS system. On Unix systems the program that issues the prompt and processes user responses is called a shell. There are usually several different shells available, the most common being the Bourne Shell (sh) and it's derivatives and the C-Shell (csh) and it's derivatives. This document will assume that the user is utilizing the GNU Bourne-Again Shell (/bin/bash) as the command interpreter. (Other command interpreters are available, but this is the most powerful and "friendly".)

Note: Much of what is discussed here is also applicable to other Unix and Unix-based systems; but the reader should consult system-specific documentation when in doubt. Features that are common to all Unix systems will use the word "Unix" in their description; features specific to IRIX will use "IRIX".