01_776130 ffirs.qxp 2/2/07 10:13 PM Page iii Professional Linux® Programming Jon Masters Richard Blum 01_776130 ffirs.qxp 2/2/07 10:13 PM Page ii 01_776130 ffirs.qxp 2/2/07 10:13 PM Page i Professional Linux® Programming 01_776130 ffirs.qxp 2/2/07 10:13 PM Page ii 01_776130 ffirs.qxp 2/2/07 10:13 PM Page iii Professional Linux® Programming Jon Masters Richard Blum 01_776130 ffirs.qxp 2/2/07 10:13 PM Page iv Professional Linux® Programming Published by Wiley Publishing, Inc. 10475 Crosspoint Boulevard Indianapolis, IN 46256 www.wiley.com Copyright © 2007 by Wiley Publishing, Inc., Indianapolis, Indiana Published simultaneously in Canada Manufactured in the United States of America 10 9 8 7 6 5 4 3 2 1 Library of Congress Cataloging-in-Publication Data: Masters, Jon, 1981- Professional Linux programming / Jon Masters, Richard Blum. p. cm. Includes index. ISBN: 978-0-471-77613-0 (paper/website) 1. Linux. 2. Operating systems (Computers) I. Blum, Richard, 1962- II. Title. 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All other trademarks are the property of their respective owners. Wiley Publishing, Inc., is not associated with any product or vendor mentioned in this book. Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic books. 01_776130 ffirs.qxp 2/2/07 10:13 PM Page v For Karin, whom I love very much.—Jon Masters To my wife Barbara.—Richard Blum 01_776130 ffirs.qxp 2/2/07 10:13 PM Page vi About the Authors Jon Masters is a 25-year-old British-born Linux kernel engineer, embedded systems specialist, and author who lives and works in the United States for Red Hat. Jon made UK history by becoming one of the youngest University students the country had ever seen, at the tender age of just 13. Having been through college twice by the time his peers were completing their first time around, and having been published over 100 times in a wide range of technical magazines, journals and books, Jon went on to work for a variety of multinational technology companies. He has worked extensively in the field of Embedded Systems, Enterprise Linux and Scientific instrumentation and has helped design anything and everything from Set Top Boxes to future NMR (MRI) imaging platforms. When not working on Enterprise Linux software for Red Hat, Jon likes to drink tea on Boston Common and read the collective works of Thomas Paine and other great American Revolutionaries of a bygone age. He dreams of a time when the world was driven not by electrons, but by wooden sailing ships and a universal struggle for the birth of modern nations. He plays the violin, and occasionally sings in choral ensembles, for which he has won several awards. For relaxation, Jon enjoys engaging in a little rock climbing. He lives in Cambridge, Massachusetts, just across the river Charles from historic Boston, and enjoys every minute of it. Jon has extensive experience in speaking about and training people to use a wide variety of Linux technologies and enjoys actively participating in many Linux User Groups the world over. Richard Blum has worked for over 18 years for a large U.S. government organization as a network and systems administrator. During this time he has had plenty of opportunities to work with Microsoft, Novell, and of course, UNIX and Linux servers. He has written applications and utilities using C, C++, Java, C#, Visual Basic, and shell script. Rich has a Bachelors of Science degree in Electrical Engineering, and a Masters of Science degree in Management, specializing in Management Information Systems, from Purdue University. He is the author of several books, including “sendmail for Linux” (2000, Sams publishing), “Running qmail” (2000, Sams publishing), “Postfix” (2001, Sams Publishing), “Open Source E-mail Security” (2001, Sams Publishing), “C# Network Programming” (2002, Sybex), “Network Performance Open Source Toolkit” (2003, John Wiley & Sons), and “Professional Assembly Language Programming” (2005, Wrox). When he is not being a computer nerd, Rich plays electric bass for the church worship and praise band, and enjoys spending time with his wife Barbara, and daughters Katie Jane and Jessica. 01_776130 ffirs.qxp 2/2/07 10:13 PM Page vii Credits Contributing Writers Graphics and Production Specialists Christopher Aillon Carrie A. Foster Katherine and David Goodwin Jennifer Mayberry Matthew Walton Barbara Moore Alicia B. South Acquisitions Editor Kit Kemper Quality Control Technicians Cynthia Fields Development Editor John Greenough Howard A. Jones Project Coordinator Production Editor Adrienne Martinez Eric Charbonneau Proofreading and Indexing Copy Editor Techbooks Foxxe Editorial Anniversary Logo Design Editorial Manager Richard Pacifico Mary Beth Wakefield Production Manager Tim Tate Vice President and Executive Group Publisher Richard Swadley Vice President and Executive Publisher Joseph B. Wikert 01_776130 ffirs.qxp 2/2/07 10:13 PM Page viii 01_776130 ffirs.qxp 2/2/07 10:13 PM Page ix Acknowledgments I sit here writing these acknowledgements on my 25th birthday, having spent many long evenings over the last year pouring over schedules, planning and even occasionally actually getting some writing done. When I first undertook to write this book, I could never have fully appreciated the amount of work it takes to put such a thing together nor the difficulties that would need to be overcome along the way. I started writing this book living just outside London and finished it less than a year later from my new home in Cambridge, Massachusetts, having decided to leave the country in the interim. Over the last year, a lot has changed for me both personally and professionally, but I am supported by a great net- work of friends and family who have helped make it possible. First and foremost I would like to thank the team I have worked with at Wiley — Debra, Adaobi, Kit, Howard and Carol as well as numerous others whose job it is to turn this manuscript into a finished book. Kit Kemper deserves special thanks for enduring my writing schedule and somehow making that just about work out in the end, as does Debra Williams-Cauley for believing that this project was a good idea in the first place. Howard Jones helped to keep me honest by doing an excellent job as my editor. This book would not exist without the inspiration I received from my good friends (and former bosses) Malcolm Buckingham and Jamie McKendry at Resonance Instruments (later Oxford Instruments), who used to moan about the lack of Linux-specific programming books. This book would also not exist with- out the kind contributions from several good friends of mine — Kat and David Goodwin, Matthew Walton, and Chris Aillon, thank you. Thanks also to Richard Blum for stepping up and joining the team once it became apparent to me that I couldn’t hope to finish this in time. You’ve all done a great job and I really do thank you very much. I have been helped along the way by my fantastic family — my parents Paula and Charles, my sisters Hannah Wrigley and Holly, my brother-in-law Joe, and occasional inspiration too from my grandmothers.