William E. Shotts - The Linux Command Line: A Complete Introduction

2ND EDITION

A Complete Introduction

by William Shotts

San Francisco

THE LINUX COMMAND LINE, 2ND EDITION. Copyright 2019 by William Shotts.

All rights reserved. No part of this work may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage or retrieval system, without the prior written permission of the copyright owner and the publisher.

ISBN-10: 1-59327-952-3
ISBN-13: 978-1-59327-952-3

Publisher: William Pollock
Production Editors: Meg Sneeringer and Serena Yang
Cover Illustration: Octopod Studios
Developmental Editor: Chris Cleveland
Technical Reviewer: Jordi Gutirrez Hermoso
Copyeditor: Kim Wimpsett
Compositors: Britt Bogan and Meg Sneeringer
Proofreader: James Fraleigh

For information on distribution, translations, or bulk sales, please contact No Starch Press, Inc. directly:
No Starch Press, Inc.
245 8th Street, San Francisco, CA 94103
phone: 1.415.863.9900;
www.nostarch.com

The Library of Congress issued the following Cataloging-in-Publication Data for the first edition:

Shotts, William E.
The Linux command line: a complete introduction / William E. Shotts, Jr.
p. cm.
Includes index.
ISBN-13: 978-1-59327-389-7 (pbk.)
ISBN-10: 1-59327-389-4 (pbk.)
1. Linux. 2. Scripting Languages (Computer science) 3. Operating systems (Computers) I. Title.
QA76.76.O63S5556 2011
005.4'32--dc23
2011029198

No Starch Press and the No Starch Press logo are registered trademarks of No Starch Press, Inc. Other product and company names mentioned herein may be the trademarks of their respective owners. Rather than use a trademark symbol with every occurrence of a trademarked name, we are using the names only in an editorial fashion and to the benefit of the trademark owner, with no intention of infringement of the trademark.

The information in this book is distributed on an As Is basis, without warranty. While every precaution has been taken in the preparation of this work, neither the author nor No Starch Press, Inc. shall have any liability to any person or entity with respect to any loss or damage caused or alleged to be caused directly or indirectly by the information contained in it.

To Karen

William Shotts has been a software professional for more than 30 years and an avid Linux user for more than 20 years. He has an extensive background in software development, including technical support, quality assurance, and documentation. He is also the creator of LinuxCommand.org, a Linux education and advocacy site featuring news, reviews, and extensive support for using the Linux command line.

Jordi Gutirrez Hermoso is a coder, mathematician, and hacker-errant. He runs Debian GNU/Linux exclusively since 2002, both at home and at work. Jordi has been involved with GNU Octave, a free numerical computing environment largely compatible with Matlab, and with Mercurial, a distributed version control system. He enjoys pure and applied mathematics, skating, swimming, and knitting. Nowadays he thinks a lot about environmental mapping, greenhouse gas emissions, and rhino conservation efforts.

I want to thank the following people, who helped make this book possible.

First, the people who inspired me:

Jenny Watson, acquisitions editor at Wiley Publishing who originally suggested that I write a shell scripting book.

John C. Dvorak, noted columnist and pundit. In an episode of his video podcast, Cranky Geeks, Mr. Dvorak described the process of writing: Hell. Write 200 words a day, and in a year, you have a novel. This advice led me to write a page a day until I had a book.

Dmitri Popov wrote an article in Free Software Magazine titled Creating a book template with Writer, which inspired me to use OpenOffice.org Writer (and later, LibreOffice Writer) for composing the text. As it turned out, it worked wonderfully.

Next, the volunteers who helped me produce the original, freely distributed version of this book (available at LinuxCommand.org):

Mark Polesky performed an extraordinary review and test of the text.

Jesse Becker, Tomasz Chrzczonowicz, Michael Levin, and Spence Miner also tested and reviewed portions of the text.

Karen M. Shotts contributed a lot of hours editing my original manuscript.

Finally, the good folks at No Starch Press who worked long and hard making the commercial version of my book:

Serena Yang, production manager; Keith Fancher, my editor; and the rest of the No Starch Press staff.

Special thanks go out to the following volunteers who provided valuable feedback incorporated into the freely distributed versions and the No Starch Press second edition: Adrian Arpidez, Hu Bo, Steve Bragg, John Burns, Paolo Casati, Heriberto Cant, Enzo Cardinal, Lixin Duan, Joshua Escamilla, Bruce Fowler, Devin Harper, Jrgen Heitmann, Jonathan Jones, Sunil Joshi, Ma Jun, Eric Kammerer, Seth King, Chris Knight, Jaroslaw Kolosowski, Jim Kovacs, Bartomiej Majka, Bashar Maree, Frank McTipps, Mike ODonnell, Justin Page, Parviz Rasoulipour, Waldo Ribeiro, Nick Rose, Satej Kumar Sahu, Mikhail Sizov, Ben Slater, Pickles Spill, Gabriel Stutzman, Francesco Turco, Wolfram Volpi, Boyang Wang, Valter Wierzba, and Christian Wuethrich.

Contributing to the second edition from No Starch Press were Serena Yang, production manager, and Meg Sneeringer, production editor; Chris Cleveland, editor; Jordi Gutirrez Hermoso, technical reviewer; and Kim Wimpsett, copy editor.

Lastly, many thanks to the readers of LinuxCommand.org, who have sent me so many kind emails. Their encouragement gave me the idea that I was really on to something!

I want to tell you a story. No, not the story of how, in 1991, Linus Torvalds wrote the first version of the Linux kernel. You can read that story in lots of Linux books. Nor am I going to tell you the story of how, some years earlier, Richard Stallman began the GNU Project to create a free Unix-like operating system. Thats an important story too, but most other Linux books have that one, as well.

No, I want to tell you the story of how you take back control of your computer.

When I began working with computers as a college student in the late 1970s, there was a revolution going on. The invention of the microprocessor had made it possible for ordinary people like you and me to actually own a computer. Its hard for many people today to imagine what the world was like when only big business and big government ran all the computers. Lets just say, you couldnt get much done.

Today, the world is very different. Computers are everywhere, from tiny wristwatches to giant data centers to everything in between. In addition to ubiquitous computers, we also have a ubiquitous network connecting them together. This has created a wondrous new age of personal empowerment and creative freedom, but over the last couple of decades something else has been happening. A few giant corporations have been imposing their control over most of the worlds computers and deciding what you can and cannot do with them. Fortunately, people from all over the world are doing something about it. They are fighting to maintain control of their computers by writing their own software. They are building Linux.