BSD Hacks

Preface

“What was it about UNIX that won my heart? . . . UNIX is mysterious when you first approach. A little intimidating, too. But despite an unadorned and often plain presentation, the discerning suitor can tell there’s lot going on under the surface.”

—Thomas Scoville, http://unix.oreilly.com/news/unix_love_0299.html

When the above-mentioned article was first published, I was still very much a BSD newbie. My spare hours were spent struggling with kernel recompiles, PPP connectivity (or lack thereof), rm and chmod disasters, and reading and rereading every bit of the then available documentation. Yet, that article gave voice to my experience, for, like the quoted author, I had stumbled upon operating system love. In other words, I was discovering how to hack on BSD.

Since then, I’ve learned that there is an unspoken commonality between the novice Unix user and the seasoned guru. It doesn’t matter whether you’ve just survived your first successful installation or you’ve just executed a complex script that will save your company time and money, the feeling is the same. It’s the excitement of venturing into unknown territory and discovering something new and wonderful. It’s that sense of accomplishment that comes with figuring something out for yourself, with finding your own solution to the problem at hand.

This book contains 100 hacks written by users who love hacking with BSD. You’ll find hacks suited to both the novice user and the seasoned veteran, as well as everyone in between. Read them in any order that suits your purpose, but keep the “onion principle” in mind. While each hack does present at least one practical solution to a problem, that’s just the outer layer. Use your imagination to peel away deeper layers, exposing new solutions as you do so.

Why BSD Hacks?

The term hacking has an unfortunate reputation in the popular press, where it often refers to someone who breaks into systems or wreaks havoc with computers. Among enthusiasts, on the other hand, the term hack refers to a “quick-n-dirty” solution to a problem or a clever way to do something. The term hacker is very much a compliment, praising someone for being creative and having the technical chops to get things done. O’Reilly’s Hacks series is an attempt to reclaim the word, document the ways people are hacking (in a good way), and pass the hacker ethic of creative participation on to a new generation of hackers. Seeing how others approach systems and problems is often the quickest way to learn about a new technology.

BSD Hacks is all about making the most of your BSD system. The BSDs of today have a proud lineage, tracing back to some of the original hackers—people who built Unix and the Internet as we know it today. As you’d expect, they faced many problems and solved problems both quickly and elegantly. We’ve collected some of that wisdom, both classic and modern, about using the command line, securing systems, keeping track of your files, making backups, and, most importantly, how to become your own BSD guru along the way.

How to Use this Book

One of the beauties of Unix is that you can be very productive with surprisingly little knowledge. Even better, each new trick you learn can shave minutes off of your day. We’ve arranged the chapters in this book by subject area, not by any suggested order of learning. Skip around to what interests you most or solves your current problem. If the current hack depends on information in another hack, we’ll include a link for you to follow.

Furthermore, the “See Also” sections at the end of individual hacks often include references such as man fortune. These refer to the manual pages installed on your machine. If you’re not familiar with these manpages, start with [Hack #89] .

How This Book Is Organized

To master BSD, you’ll have to understand several topics. We’ve arranged the hacks loosely into chapters. They are:

Chapter 1 Customizing the User Environment

Though modern BSDs have myriad graphical applications and utilities, the combined wisdom of 35 years of command-line programs is just a shell away. This chapter demonstrates how to make the most of the command line, customizing it to your needs and preferences.

Chapter 2 Dealing with Files and Filesystems

What good is knowing Unix commands if you have no files? You have to slice, dice, and store data somewhere. This chapter explains techniques for finding and processing information, whether it’s on your machine or on a server elsewhere.

Chapter 3 The Boot and Login Environments

The best-laid security plans of administrators often go out the window when users enter the picture. Keeping the bad guys off of sensitive machines requires a two-pronged approach: protecting normal user accounts through good password policies and protecting the boxes physically. This chapter explores several options for customizing and securing the boot and login processes.

Chapter 4 Backing Up

After you start creating files, you’re bound to run across data you can’t afford to lose. That’s where backups come in. This chapter offers several ideas for various methods of ensuring that your precious data will persist in the face of tragedy.

Chapter 5 Networking Hacks

Unless you’re a die-hard individualist, you’re likely connected to a network. That fact presents several new opportunities for clever hacks as well as mystifying failures. This chapter illuminates ways to take advantage of your network connection.

Chapter 6 Securing the System

Security is as much a mindset as it is a process. Knowing the tools at your disposal will help. This chapter delves into multiple tools and ideas for increasing the security of your systems, whether keeping out the bad guys or staying on top of updates.

Chapter 7 Going Beyond the Basics

With years and years of refinement, the BSDs provide powerful and maintainable environments. Are you taking full advantage of everything your system has to offer? This chapter pushes the envelope of what you can accomplish.

Chapter 8 Keeping Up-to-Date

No bragging about BSD is complete without mentioning the ports or packages system that keeps thousands of applications right at your fingertips. Keeping up-to-date could never be easier, could it? This chapter tackles the subject of installing and updating software, including the core system.

Chapter 9 Grokking BSD

You cannot be a true BSD master until you grok the Unix mindset. How did the gurus become gurus? Is the true path still open? This chapter reveals some secrets of the masters and has a little fun along the way.

Conventions Used in This Book

This book uses the following typographical conventions:

Italic

Indicates new terms, URLs, email addresses, filenames, pathnames, and directories.

Constant width

Indicates commands, options, switches, variables, attributes, functions, user and group names, the contents of files, and the output from commands.

Constant width bold

In code examples, shows commands or other text that should be typed literally by the user.

Constant width italic

Shows text that should be replaced with user-supplied values.

Color

The second color is used to indicate a cross-reference within the text.

Tip

This icon signifies a tip, suggestion, or general note.

Warning

This icon indicates a warning or caution.

The thermometer icons, found next to each hack, indicate the relative complexity of the hack:

beginner

moderate

expert

Using Code Examples

This book is here to help you get your job done. In general, you may use the code in this book in your programs and documentation. You do not need to contact us for permission unless you’re reproducing a significant portion of the code. For example, writing a program that uses several chunks of code from this book does not require permission. Selling or distributing a CD-ROM of examples from O’Reilly books does require permission. Answering a question by citing this book and quoting example code does not require permission. Incorporating a significant amount of example code from this book into your product’s documentation does require permission.

We appreciate, but do not require, attribution. An attribution usually includes the title, author, publisher, and ISBN, for example: "BSD Hacks by Dru Lavigne. Copyright 2004 O’Reilly Media, Inc., 0-596-00679-9.”

If you feel your use of code examples falls outside fair use or the permission given here, feel free to contact us at [e-mail].

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