TEAM LinG - Live, Informative, Non-cost and Genuine! 00 0672323982 FM 6/18/02 2:05 PM Page i Teach Yourself Unix System Administration 24 in Hours Dave Taylor 800 East 96th St., Indianapolis, Indiana, 46240 USA TEAM LinG - Live, Informative, Non-cost and Genuine! 00 0672323982 FM 6/18/02 2:05 PM Page ii Sams Teach Yourself Unix System ACQUISITIONSEDITOR Kathryn Purdum Administration in 24 Hours DEVELOPMENTEDITOR Copyright © 2003 by Sams Publishing Heather Goodell All rights reserved. No part of this book shall be reproduced,stored in a MANAGINGEDITOR retrieval system,or transmitted by any means,electronic,mechanical,photo- Charlotte Clapp copying,recording,or otherwise,without written permission from the pub- PROJECTEDITOR lisher. No patent liability is assumed with respect to the use of the information Elizabeth Finney contained herein. Although every precaution has been taken in the preparation of this book,the publisher and author assume no responsibility for errors or PRODUCTIONEDITOR omissions. Nor is any liability assumed for damages resulting from the use of Seth Kerney the information contained herein. INDEXER International Standard Book Number:0-672-32398-2 Larry Sweazy Library of Congress Catalog Card Number:2001099557 PROOFREADER Suzanne Thomas Printed in the United States of America TECHNICALEDITORS First Printing:July 2002 Dee-Ann LeBlanc 05 04 03 02 4 3 2 1 David Ennis Trademarks TEAMCOORDINATOR Amy Patton All terms mentioned in this book that are known to be trademarks or service marks have been appropriately capitalized. Sams Publishing cannot attest to the INTERIORDESIGNER accuracy of this information. Use of a term in this book should not be regarded Gary Adair as affecting the validity of any trademark or service mark. COVERDESIGNER Alan Clements Warning and Disclaimer PAGELAYOUT Every effort has been made to make this book as complete and as accurate as Stacey Richwine-DeRome possible,but no warranty or fitness is implied. The information provided is on an “as is”basis. The author and the publisher shall have neither liability nor responsibility to any person or entity with respect to any loss or damages aris- ing from the information contained in this book. TEAM LinG - Live, Informative, Non-cost and Genuine! 00 0672323982 FM 6/18/02 2:05 PM Page iii Contents at a Glance Introduction 1 PART I Installing Unix 5 Hour 1 Installing Unix 7 PART II Introduction to the Filesystem 21 Hour 2 An Unsung Resource:Unix Documentation 23 3 Disk Usage 41 4 File Ownership 67 PART III User & Package Management 83 Hour 5 Working with User Accounts 85 6 Account Management 107 7 Large File Management & Backups 133 8 Unix Package Management 161 PART IV Advanced Filesystem Topics 179 Hour 9 Fixing Broken Disks 181 10 Adding Disks to Your System 197 11 Multiple Boot Configurations 217 12 Managing Disk Quotas 231 PART V Process & System Controls 245 Hour 13 Changing System State 247 14 Exploring Processes 265 15 Running Jobs in the Future 285 16 Managing Your Log Files 301 PART VI Network Topics 325 Hour 17 Basic Network Configuration 327 18 Running Your Own Name Server 353 19 Running Internet Services 373 20 Working with E-mail 391 TEAM LinG - Live, Informative, Non-cost and Genuine! 00 0672323982 FM 6/18/02 2:05 PM Page iv PART VII Web Server Management & Shell Programming 413 Hour 21 Shell Scripting:The Administrator’s Swiss Army Knife 415 22 Power Scripting with awkand Perl 443 23 Introduction to the Apache Web Server 457 24 Virtual Hosts with Apache 473 Index 483 TEAM LinG - Live, Informative, Non-cost and Genuine! 00 0672323982 FM 6/18/02 2:05 PM Page v Contents Introduction 1 PART I Installing Unix 5 HOUR 1 Installing Unix 7 Unix Installation Options........................................................................................8 Basic Red Hat Linux Installation..........................................................................10 Installation Help Online........................................................................................16 Summary................................................................................................................17 Q&A......................................................................................................................17 Workshop ..............................................................................................................18 Quiz..................................................................................................................18 Answers............................................................................................................18 PART II Introduction to the Filesystem 21 HOUR 2 An Unsung Resource: Unix Documentation 23 The Philosophy of Digging....................................................................................23 apropos:The Administrator’s Secret Weapon ....................................................24 Task 2.1:aproposand the WhatisDatabase..................................................24 Exploring the whatisDatabase............................................................................32 Task 2.2:What’s Inside the whatisDatabase ................................................32 Finding Commands................................................................................................34 Task 2.3:Which Command Are You Running? ..............................................34 Digging Around in Executable Binaries................................................................37 Task 2.4:The stringsCommand ..................................................................37 Summary................................................................................................................39 Q&A......................................................................................................................39 Workshop ..............................................................................................................39 Quiz..................................................................................................................39 Answers............................................................................................................40 HOUR 3 Disk Usage 41 Physical Disks and Partitions................................................................................41 Task 3.1:Exploring Partitions..........................................................................42 A Closer Look with du..........................................................................................47 Task 3.2:Using duto Ascertain Directory Sizes ............................................47 Simplifying Analysis with sort............................................................................52 Task 3.3:Piping Output to sort......................................................................53 Identifying the Biggest Files..................................................................................55 Task 3.4:Finding Big Files..............................................................................55 TEAM LinG - Live, Informative, Non-cost and Genuine! 00 0672323982 FM 6/18/02 2:05 PM Page vi vi Sams Teach Yourself Unix Administration in 24 Hours Keeping Track of Users:diskhogs ......................................................................59 Task 3.5:This Little Piggy Stayed Home?......................................................59 Summary................................................................................................................64 Q&A......................................................................................................................64 Workshop ..............................................................................................................64 Quiz..................................................................................................................64 Answers............................................................................................................65 HOUR 4 File Ownership 67 Starting at the Beginning:Permission Strings......................................................67 Task 4.1:The Basics of File Permissions........................................................68 Ownership and /etc/passwd................................................................................70 Task 4.2:Understanding /etc/passwd............................................................70 Understanding Unix Groups and /etc/group......................................................73 Task 4.3:Groups and the /etc/groupfile......................................................74 Using Groups to Control Access ..........................................................................77 Task 4.4:Access Control with Groups ............................................................77 Summary................................................................................................................80 Q&A......................................................................................................................80 Workshop ..............................................................................................................80 Questions..........................................................................................................80 Answers............................................................................................................81 PART III User & Package Management 83 HOUR 5 Working with User Accounts 85 Understanding the /etc/passwdFile ..................................................................86 Task 5.1:Exploring /etc/passwd ..................................................................86 Password Files in BSD/Mac OS X........................................................................91 Task 5.2:Accounts and the Password File in Darwin......................................91 Adding Users and the adduserScript..................................................................94 Task 5.3:Adding Users in a Conventional Unix World ..................................95 Adding Users in a NetInfo World........................................................................100 Task 5.4:The Darwin Version of adduser....................................................100 Summary..............................................................................................................103 Q&A....................................................................................................................103 Workshop ............................................................................................................104 Quiz................................................................................................................104 Answers..........................................................................................................104 HOUR 6 Accounts Management 83 Ways to Suspend User Accounts ........................................................................108 Task 6.1:Suspending Users............................................................................108 Deleting User Accounts ......................................................................................112 Task 6.2:Deleting User Accounts..................................................................112 TEAM LinG - Live, Informative, Non-cost and Genuine! 00 0672323982 FM 6/18/02 2:05 PM Page vii Contents vii Linux Account Management Tools114 Task 6.3:Linux Admin Tools ........................................................................115 Solaris Account Management Tools....................................................................121 Task 6.4:Solaris Account Administration Tools............................................121 Password Aging ..................................................................................................126 Task 6.5:Tools for Managing Password Aging ............................................126 Summary..............................................................................................................129 Q&A....................................................................................................................130 Workshop ............................................................................................................130 Quiz................................................................................................................130 Answers..........................................................................................................130 HOUR 7 Large File Management and Backups 133 Shrinking Big Files with compress....................................................................134 Task 7.1:Working with compress ................................................................134 ThegzipAlternative ..........................................................................................138 Task 7.2:Working with gzip ........................................................................139 A Zippy Tour of zip............................................................................................145 Task 7.3:Working with zip ..........................................................................145 Copying Directory Trees with tar......................................................................148 Task 7.4:Working with tar ..........................................................................149 dumpand System Backups ..................................................................................153 Task 7.5:Incremental Backups......................................................................153 Summary..............................................................................................................158 Q&A....................................................................................................................158 Workshop ............................................................................................................159 Quiz................................................................................................................159 Answers..........................................................................................................159 HOUR 8 Unix Package Management 161 Red Hat Package Manager and Linux ................................................................162 Task 8.1:Working with RPM ........................................................................162 Adding New RPM Packages from the Internet ..................................................165 Task 8.2:Installing New Web-Based RPM Packages....................................165 Package Management in Darwin ........................................................................168 Task 8.3:Installing and Working with fink..................................................168 Package Management in Solaris..........................................................................172 Task 8.4:Managing Packages in Solaris........................................................172 Summary..............................................................................................................177 Q&A....................................................................................................................177 Workshop ............................................................................................................177 Quiz................................................................................................................177 Answers..........................................................................................................177 TEAM LinG - Live, Informative, Non-cost and Genuine! 00 0672323982 FM 6/18/02 2:05 PM Page viii viii Sams Teach Yourself Unix Administration in 24 Hours PART IV Advanced File System Topics 179 Hour 9 Fixing Broken Disks 181 Introduction to fsck............................................................................................182 Task 9.1:Getting Started with fsck..............................................................183 Fixing Problems with fsck..................................................................................186 Task 9.2:Fixing Disk Problems with fsck....................................................186 Single-User Mode................................................................................................190 Task 9.3:Single-User Mode in Darwin..........................................................191 Don’t Panic! ........................................................................................................193 Summary..............................................................................................................194 Q&A....................................................................................................................194 Workshop ............................................................................................................195 Quiz................................................................................................................195 Answers..........................................................................................................195 HOUR 10 Adding Disks to Your System 197 Formatting Disks with fdisk..............................................................................198 Task 10.1:Formatting a Disk with fdisk......................................................199 Adding a Filesystem with mke2fs ......................................................................203 Task 10.2:Making a Filesystem with mke2fs ..............................................204 Mounting the New Disk......................................................................................208 Task 10.3:Adding New Drives to Your System ............................................208 Fine-tuning Your /etc/fstabConfiguration File..............................................212 Task 10.4:Creating the Perfect /etc/fstabFile..........................................212 Summary..............................................................................................................215 Q&A....................................................................................................................215 Workshop ............................................................................................................216 Quiz................................................................................................................216 Answers..........................................................................................................216 HOUR 11 Multiple Boot Configurations 217 The Theory of Dual-Booting ..............................................................................218 Task 11.1:Partitioning Disks for Dual Boot..................................................219 Dual-Boot Configurations with LILO ................................................................220 Task 11.2:Configuring LILO........................................................................221 Dual-Boot Configurations with GRUB ..............................................................223 Task 11.3:Configuring GRUB ......................................................................223 Other Solutions for Other Unixes........................................................................226 Task 11.4:Learning About Virtual Machines................................................227 TEAM LinG - Live, Informative, Non-cost and Genuine! 00 0672323982 FM 6/18/02 2:05 PM Page ix Contents ix Summary..............................................................................................................228 Q&A....................................................................................................................229 Workshop ............................................................................................................229 Quiz................................................................................................................229 Answers..........................................................................................................230 HOUR 12 Managing Disk Quotas 231 Implementing a Disk-Quota Policy ....................................................................232 Task 12.1:Implementing Quotas....................................................................232 Quota Nuances on Other Unixes ........................................................................237 Task 12.2:Quotas on Other Systems ............................................................237 Creating Your Own Quota System with find ....................................................239 Task 12.3:Disk-Quotas with find ................................................................239 Summary..............................................................................................................243 Q&A ..............................................................................................................243 Workshop ............................................................................................................243 Quiz................................................................................................................243 Answers..........................................................................................................244 PART V Process & System Controls 245 HOUR 13 Changing System State 247 Configuring and Working with the initProcess................................................248 Task 13.1:The initProcess and Configuration ..........................................248 Enabling Specific Services at Different Run Levels ..........................................254 Task 13.2:Configuring Your System for Run Levels....................................255 Shutting Down Your System the Right Way........................................................259 Task 13.3:Safe Shutdowns and Reboots ......................................................260 Summary..............................................................................................................262 Q&A....................................................................................................................262 Workshop ............................................................................................................262 Quiz................................................................................................................263 Answers..........................................................................................................263 HOUR 14 Exploring Processes 265 The Secret Life of Process IDs............................................................................266 Task 14.1:Process ID Information................................................................266 Examining Processes with the psCommand......................................................267 Task 14.2:Exploring ps ................................................................................267 A Typical Sysadmin Task:What’s artsd?..........................................................273 Task 14.3:A Little Unix Detective Work ......................................................273 Process Priorities..................................................................................................276 Task 14.4:Managing Process Priorities ........................................................276 TEAM LinG - Live, Informative, Non-cost and Genuine!