Book Preface

To The Student

This text is a basic introduction to the complex world of the Unix operating system. Here, you will find information about several aspects of working with Unix, from simple personal tasks to shell programming and system administration. Unix is a powerful and ever-evolving system, which is now available in variants designed for every hardware platform and with configurations to suit any preferences or needs. It powers much of the world’s academic and business information technology, and is increasingly popular for home networks and machines.

You may find Unix intimidating, especially if you have not worked with text-based operating systems before. Although it might be unfamiliar territory, explore the systems available to you and practice the various commands you see in this book or find elsewhere. You will come to see that, although the user interface can initially be uncomfortable, working with Unix is much like working on any other operating system: especially if you are working on a Unix installation which offers a graphical user interface, some of which are virtually indistinguishable from Windows or MacOS.

If you have a spare computer available to you, we strongly encourage you to consider downloading and installing a Unix variant for your own practice and exploration. The most popular Unix variants for personal computers are Linux and FreeBSD. There are more than a hundred Linux variants available on the Internet, but the Red Hat and Debian distributions tend to be the friendliest for new users. FreeBSD has only one distribution, but it is also good for newcomers. While you are learning, it would be best to keep your Unix machine separate from your regular home computer, should you have one. You can run Linux on a 486, as long as you work primarily in text mode. Using the graphical interfaces can slow the system significantly if there is not enough RAM or a fast enough chip. Unix is best learned hands on.

Whether this is the only Unix course you take or whether you are interested in pursuing a career related to Unix administration or development, this course will expose you to the various elements that make up the day of most professional Unix people. The Unix employment outlook is still vibrant, especially in academic and large corporate arenas. Even those who plan to work with Microsoft or Apple products will benefit from Unix knowledge since heterogeneous networks are increasingly the norm rather than the deviation.

To The Teacher

This text is designed to provide an overview of several critical areas of the Unix operating system. With this text, you can expose your students to a range of activities related to Unix, from simple filesystem navigation to scripting with sed and awk, as well as the various functions which system administrators perform regularly. No matter what the focus of your particular course – from a survey of operating systems to a class designed for IT majors – you should find information here which will support your classroom activities.

The text is divided into several sections, so that it can be used in a variety of courses with different syllabi and emphasis. Most instructors will use the first two sections in their courses, especially if their students have little experience with multi-user operating systems.

• Chapters 1-6 provide an overview of Unix history, how the operating system works, how commands are given and processed,  the file system, and jobs and processes. This section also introduces the shell environment. The bash shell is the default shell used in this book.
• Chapters 7-9 introduce your students to common Unix applications: various text editors, with an emphasis on vi, and some popular Internet applications which your students can put to use immediately if you are working in a networked environment. For those instructors who use electronic mail to communicate with their students, several e-mail clients are covered in this section.
• Chapters 10 and 11 introduce networking. From the most basic concepts of Unix networking to a case study in which students can build a small local network and connect it to the Internet, the ideas presented here are useful for students no matter what their major or eventual career goal.
• Chapters 12-15 concentrate on bash shell programming. Some instructors may not cover this material in their courses, while others find that shell programming is an excellent introduction to programming in general, especially if students are required to take more complex programming courses in their course of study. The basic concepts of shell scripting are introduced here, with increasingly complex scripts and examples.
• Chapters 16-19 are focused on system administration. Since sysadmin jobs are one of the most common destinations for Unix-skilled students, the jobs that routinely make up an administrator’s day are an important focus. These chapters introduce user and disk management, working with software, the X Window System, and running networked services: printing, Internet services, and remote access. Attention is also paid to security management and to working with disabled users.
• The appendices contain a brief command compendium, a glossary, a set of configuration files which you can use for examples or illustration, and a set of URLs for further study or exploration.

The text is general enough that it can be used with almost every Unix variant, and all the variants which are likely to be found in an academic setting. Of course, hands on work is the best way to gain comfort with Unix, and we encourage students (and instructors) to consider installing Linux or FreeBSD on a spare machine. This allows students to explore root-restricted programs and functions, as well as demystifying the operating system through familiarity. Red Hat or Debian Linux, or FreeBSD, are the most user-friendly choices. If your academic set-up offers both graphical interfaces and text mode, note that we have concentrated on text mode, or terminal window access, throughout the book since it is hard to predict how many systems still run as text-only.