Blum Richard - Linux Command Line and Shell Scripting Bible

Linux Command Line and Shell Scripting Bible, Second Edition Published by Wiley Publishing, Inc. 10475 Crosspoint Boulevard Indianapolis, IN 46256 www.wiley.com Copyright 2011 by Wiley Publishing, Inc., Indianapolis, Indiana Published simultaneously in Canada ISBN: 978-1-118-00442-5 ISBN: 978-1-118-08777-0 (ebk) ISBN: 978-1-118-08778-7 (ebk) ISBN: 978-1-118-08779-4 (ebk) No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except as permitted under Sections 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978) 646-8600. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, (201) 748-6011, fax (201) 748-6008, or online at http://www.wiley.com/go/permissions. Limit of Liability/Disclaimer of Warranty: The publisher and the author make no representations or warranties with respect to the accuracy or completeness of the contents of this work and specifically disclaim all warranties, including without limitation warranties of fitness for a particular purpose. No warranty may be created or extended by sales or promotional materials. The advice and strategies contained herein may not be suitable for every situation.

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Wiley Publishing, Inc. is not associated with any product or vendor mentioned in this book. To the Lord God Almighty, in whom are hidden all the treasures of wisdom and knowledge. Colossians 2:3 Credits Acquisitions Editor Mary James Project Editor Brian Herrmann Technical Editor Jack Cox Production Editor Daniel Scribner Copy Editor Nancy Rapoport Editorial Director Robyn B. Siesky Editorial Manager Mary Beth Wakefield Freelancer Editorial Manager Rosemarie Graham Marketing Manager Ashley Zurcher Production Manager Tim Tate Vice President and Executive Group Publisher Richard Swadley Vice President and Executive Publisher Barry Pruett Associate Publisher Jim Minatel Project Coordinator, Cover Katherine Crocker Proofreader Publication Services, Inc. Indexer Robert Swanson Cover Designer Ryan Sneed Cover Image Joyce Haughey About the Authors Richard Blum has worked in the IT industry for more than 20 years as both a systems and network administrator, and has published numerous Linux and open source books.

He has administered UNIX, Linux, Novell, and Microsoft servers, as well as helped design and maintain a 3,500 user network utilizing Cisco switches and routers. He has used Linux servers and shell scripts to perform automated network monitoring, and has written shell scripts in most of the common Linux shell environments. Rich is an online instructor for an Introduction to Linux course that is used by colleges and universities across the U.S. When he's not being a computer nerd, Rich plays electric bass in a couple of different church worship bands, and enjoys spending time with his wife Barbara, and two daughters Katie Jane and Jessica. Christine Bresnahan starting working with computers more than 25 years ago in the IT industry as a system administrator. Christine is currently an Adjunct Professor at Ivy Tech Community College in Indianapolis, Indiana, teaching Linux system administration, Linux security, and Windows security classes.

About the Technical Editor Jack Cox is a Senior Manager with CapTech Ventures in Richmond, VA. He has more than 25 years of experience in IT, spanning a broad range of disciplines including mobile computing, transaction processing, RFID, Java development, and cryptography. Jack enjoys life in Richmond with his lovely wife and rambunctious children. Outside of technology, his interests include church, his children, and extended family. Acknowledgments First, all glory and praise go to God, who through His Son, Jesus Christ, makes all things possible, and gives us the gift of eternal life. Many thanks go to the fantastic team of people at John Wiley & Sons for their outstanding work on this project.

Thanks to Mary James, the acquisitions editor, for offering us the opportunity to work on this book. Also thanks to Brian Herrmann, the project editor, for keeping things on track and making this book more presentable. Thanks, Brian, for all your hard work and diligence. The technical editor, Jack Cox, did a wonderful job of double checking all the work in the book, plus making suggestions to improve the content. Thanks to Nancy Rapoport, the copy editor, for her endless patience and diligence to make our work readable. We would also like to thank Carole McClendon at Waterside Productions, Inc., for arranging this opportunity for us, and for helping us out in our writing careers.

Christine would like to thank her husband, Timothy, for his encouragement, patience, and willingness to listen, even when he has no idea what she is talking about. Introduction Welcome to the second edition of Linux Command Line and Shell Scripting Bible . Like all books in the Bible series, you can expect to find both hands-on tutorials and real-world information, as well as reference and background information that provides a context for what you are learning. This book is a fairly comprehensive resource on the Linux command line and shell commands. By the time you have completed Linux Command Line and Shell Scripting Bible you will be well prepared to write your own shell scripts that can automate practically any task on your Linux system. Who Should Read This Book If you're a system administrator in a Linux environment, you'll benefit greatly by knowing how to write shell scripts.

The book doesn't walk you through the process of setting up a Linux system, but once you have it running you'll want to start automating some of the routine administrative tasks. That's where shell scripting comes in, and that's where this book will help you out. This book will demonstrate how to automate any administrative task using shell scripts, from monitoring system statistics and data files to generating reports for your boss. If you're a home Linux enthusiast, you'll also benefit from Linux Command Line and Shell Scripting Bible . Nowadays, it's easy to get lost in the graphical world of pre-built widgets. Most desktop Linux distributions try their best to hide the Linux system from the typical user.