Red Hat Linux

Lemasters, Darlena Murray, Julie Searls, Sossity Smith Overview iii Introduction xxiii Part I Introduction and Installation of Linux 1 Introduction to Red Hat Linux and UNIX 3 2 Installa

Publisher Dean Miller

Executive Editor Jeff Koch

Managing Editor Sarah Kearns

Senior Indexer Ginny Bess

Director of Software

and User Services Cheryl Willoughby

Brand Director Alan Bower

This book is dedicated to TM3 and

Associates Thanks, guys

retrieval system, or transmitted by any

means, electronic, mechanical,

photocopying, recording, or otherwise,

without written permission from the

publisher No patent liability is assumed with respect to the use of the

information contained herein Although everyprecaution has been taken in

the preparation of this book, the publisher and author assume no responsibility

for errors or omissions Neither is any liabilityassumed for damages

resulting from the use of the information

contained herein For information,

address Sams Publishing, 201 W 103rd St., Indianapolis, IN 46290

International Standard Book Number: 31173-9

0-672-Library of Congress Catalog Card Number: 97-68008

01 00 99 98 4 3 2 1

Interpretation of the printing code: The

rightmost double-digit number is

the year of the book’s printing; the rightmost single digit, the number of the

book’s printing For example, a printing code

of 98-1 shows that the first

printing of the book occurred in 1998

Composed in AGaramond and MCPdigital by Macmillan Computer

service marks have been appropriately

capitalized Sams Publishing cannot

attest to the accuracy of this information Use of a term in this book should

not be regarded as affecting the validity of any trademark or service mark

Red Hat Linux is a trademark of Red Hat Software.

Carolyn Linn, Kate Talbot,

Michael Brumitt, Chuck

Hutchinson, Nancy Albright

Indexer

Cheryl Jackson

Technical Reviewers

Bill Ball, Sriranga R.

Veeraraghavan, Robin Burk

Bryan Flores, Julie Geeting,

Kay Hoskin, Christy M.

Lemasters, Darlena Murray,

Julie Searls, Sossity Smith

Overview iii

Introduction xxiii

Part I Introduction and Installation of Linux

1 Introduction to Red Hat Linux and UNIX 3

2 Installation of Your Red Hat System 11

3 LILO 27

Part II Configuring Other Servers

4 System Startup and Shutdown 37

5 Configuring and Building Kernels 53

6 Common Desktop Environment 75

7 SMTP and POP 97

8 FTP 131

9 Apache Server 153

10 X Window 175

Part III Hardware Connectivity and Devices

11 Filesystems, Disks, and Other Devices

195

12 Printing with Linux 229

13 TCP/IP Network Management 243

Part IV System Administration and

Management

14 Getting Started with Red Hat Linux 299

15 Essential System Administration 319

16 Advanced System Administration 341

17 GNU Project Utilities 351

18 Backup and Restore 373

Part V Dealing with Others

19 User Accounts and Logins 383

Part VI Automation, Programming, and

Modifying Source Code

Part VII Appendixes

A The Linux Documentation Project 607

B Top 50 Linux Commands and Utilities 611

C The Linux Documentation Project Copyright

Part I Introduction and Installation of Linux

1 Introduction to Red Hat Linux and

UNIX 3

Advantages of

Linux 5

Copyright and

Warranty 7

Where to Get Red Hat

Linux 7System

Requirements 7

2 Installation of Your Red Hat System

Be Prepared, Be Very

Prepared! 12

Installing Red Hat

Linux 13

Creating the Boot and Supplemental

Disks 13

Installing Without Using a Boot

Floppy 14

Virtual

Consoles

14

Dialog Boxes

14

Step-by-Step Installation

15

Booting

15

The Installation Program

15 Selecting an Installation Method 17

CD-ROM Installation

17

The Red Hat Package Manager

25 RPM Usage

25

Summary

26

3 LILO 27 Installing and Configuring LILO 28

Configuring LILO

29

Using LOADLIN.EXE to Boot

Linux 33

How to Uninstall

LILO 33

Summary 33

Part II Configuring Other Servers

4 System Startup and Shutdown 37

The Boot

Process 38

The Initialization Process and Startup

halt and reboot

45

When the System

Crashes 46

Running as

Root

47

Creating a Boot Disk

47 Your File Toolbox

48

Red Hat to the Rescue! When the System Won’t Boot 49

For More Information

50

Summary

51

5 Configuring and Building Kernels 53 An Introduction to the Linux Kernel 54

Acquiring the Source Tree 55

Patching the Source Tree 57

Modules

57

Configuring the Linux Kernel 58

Starting the Configuration

58

Stepping Through the Menus 59

Final Notes About

Configuration 70

Building the

Kernel 70

Installing the

Kernel 72

Recovering from Faulty

Kernels 73Summary 73

6 Common Desktop Environment 75

Installation 76

Getting Started with the

CDE 77Logging in to the

CDE 77

The Desktop

Environment 78

Customizing Your

Session 81

The Style

Manager 81

The Front

Panel 82

Advanced

Customizations

84

Creating New Actions

87

Creating and Modifying Subpanels 90

Restoring a Session When Something Goes Wrong 91

Executing Applications and Commands at Login 92

Executing Commands at Logout 93

The Help Viewer

93

Using the Help Viewer

93

Context-Sensitive Help

93 vii Adding Help to Icons

94 Help Topics

95

Summary

96

7 SMTP and POP 97

SMTP

98

Internet Mail Protocols

99

The Domain Name System and E-mail 100

sendmail’s Jobs

104

sendmail’s Auxiliary Files 105

The Aliases File

105

Setting Up sendmail 106

sendmail.cf—The Configuration File 109

Testing sendmail and sendmail.cf 123

POP

124

Configuring a POP Server

125 Managing Bulletins

128

Summary

129

8 FTP 131

Getting and Installing the FTP

Server 132

How the FTP Server Works

133 Configuring Your FTP Server 134

Controlling Access—The /etc/ftpaccess File 135

Converting Files On-the-Fly—The /etc/ftpconversions File 147 Configuring Host Access—The /etc/ftphosts File 149

The FTP Log File—/var/log/xferlog 150

FTP Administrative Tools

151 ftpshut

151

ftpwho

151

ftpcount

152

Summary

152

9 Apache Server 153 Server Installation

154

Runtime Server Configuration Settings 155

Editing httpd.conf

155Editing srm.conf

158

Editing access.conf

158Configuring an inetd

Server 159

Configuring inetd

160

Running the Web Server for the First

Time 162

Starting a Standalone

Server 163Starting an inetd

Server 163

Script 164

The stop

Script 164

The restart

Script 164

Configuration File

Listings 165

Summary 173

10 X Window 175

Setting Up Your XFree86

System 176The XF86Config

File 176

Using Xconfigurator

177

Examining the XF86Config

File 177

The File

Pathnames 178

The Keyboard

Section 179

The Pointer

Section 179

The Server

Section 181

Setting Up Video

Modes

182 International Keyboard Layout for XFree86 184

The xinitrc File

185

The Personal X Resource File 186

Using xdm

187

Configuration of the Window Manager 188

Compiling Programs That Use X 188

Some Common Problems

189

Compiling Sources for XFree86 190

Summary

191

Part III Hardware Connectivity and Devices 11 Filesystems, Disks, and Other Devices 195 Block Devices

197

Filesystems

197

The mount

Command

198

Setting Up Filesystems

202

The Red Hat File System Manager 202

Editing /etc/fstab Manually 203

Creating New Filesystems

204

Repairing Filesystems

207

Hardware

209

Hard Disks

209

Floppy Disks

211

CD-ROM Drives

212

Loopback Devices

213

Other Block Devices

215

Character

Devices

217

Parallel Ports

217

Tape Drives

218

Terminals

220

Serial Communications

222

Generic SCSI Devices

223

CD-ROM Recorders

224

Testing CD Images

224

Other Character Devices

224 Summary

228

12 Printing with Linux 229 Printer Devices

230

How Do I

Print?

231

The RHS Linux Print System Manager 232

Remote and LAN Printers

232 Local Printers

233

Linux Printing Commands

234

Simple Formatting

235

Other Helpful Printer Programs and Filters 236

APSfilter

236

BubbleTools

236

magicfilter

236

PostScript Printers

237

Enhanced Printer Spooler 237

System

Accounting

237

Some Program Tips

237

emacs

237

Applixware for Linux

238 Other Helpful Programs

239

xv

239

pbm Utilities

240

Ghostview

240

For More Information

240

Summary

241

13 TCP/IP Network Management 243 An Introduction to Networking

244 What Is an IP Number?

244

A TCP/IP

Primer

244

Subnetworking

246

Determining the Broadcast Address 247

The Next Generation of IP, IPv6 247

Getting a New IP Address

248 Contents Red Hat Linux, Second Edition UNLEASHED x The Network Card Solution

249 Stock Network Configuration

250 Using ifconfig

254 Using route

256

The Domain Name Service

258 Before DNS—The /etc/hosts File 258

Configuring the DNS Client: /etc/resolv.conf 259

The Software of

DNS 259

Configuring DNS

Servers 261

The Network Information

Service 269

A Brief

History 269

Understanding

NIS 270

Configuring a Master NIS

Server 271

Configuring an NIS

client 274Configuring an NIS Secondary

Server 276

The Network File

System 280

Installing

NFS 281

Starting and Stopping the NFS

daemons 282

Configuring

NFS 282

Connecting to the Net with

PPP 288

Simple

Client 289

On-Demand

Dialing 293

Summary 294

Part IV System Administration and

Management

14 Getting Started with Red Hat Linux 299

Organization 300

/bin and /sbin

300

/etc

301

/home

303

/mnt

303

/tmp and /var

303

304

RPM 305

Major Modes and Common

Options 305

Installing

Packages 306

Upgrading

Packages 309

Uninstalling

Packages 309

Querying

Packages 310

Verifying

Packages 313

Introduction to

glint 314

Summary 317

xi

15 Essential System Administration 319

Handling the All-Powerful Root

Account 320

Maintaining the System—Implementing

Changes 321

Planning

Processes 322

Creating a Back-Out

Plan 322Making Changes in Small

Increments 322

Developing a Test

Plan 323

Communicating Effectively and in a Timely Manner 323

Getting

Help 328

Man

Pages 329

E-mail 331

Red Hat Mailing Lists and

Newsgroups 332

Other

Newsgroups 334

Problem Solving—

Logs 335

login.access 336

Other Files That Deny or Allow Users or Hosts 337

syslog 337

Wine—Accessing Windows Applications

Under Linux 338

New Releases of

Wine 339

Where to Get Copies of

Wine 339

Installation and Problems Running Windows Applications 339

Summary 340

16 Advanced System Administration 341

Basic Performance

Analysis 342

Determining CPU

Usage 342

top 344

How Much Swap Is

Enough? 347

Momma Always Said to Be

Nice! 348

Summary 349

17 GNU Project Utilities 351

File

Utilities 352

Listing Directory

Contents 352

File

Operations 354

Changing File

Attributes 355

Disk

Usage 358

Find

Utilities 358

locate 358

find 359

xargs 361

Shell

Utilities 363

Who’s Who in

GNU 363

The id

Commands 364

Contents

Red Hat Linux, Second Edition

UNLEASHED

The head and tail

Commands 366

The split

Command 368

Counting

Words 369

Summary 371

18 Backup and Restore 373

Qualities of a Good

Backup 374

Selecting a Backup

Medium 375

Selecting a Backup

Tool 375

Backup

Strategy 376

Performing Backups with tar and cpio

377

Restoring

Files 378

What Is on the

Tape? 378

Summary 379

Part V Dealing with Others

19 User Accounts and Logins 383

Adding

Users 384

Editing etc/passwd

384Editing /etc/group

387Creating a Home Directory and Copying Files

to the New

Home 389

Changing Ownerships and

Permissions 389

Setting the

Password 389

Changing User

Properties 390

Temporarily Disabling a

User 390

The Login and How to Become a Specific User 390

The su

Command 391

Searching 391

who 392

finger 392

Summary 393

Tools 397

Knowledge

Gathering 399

Danger, Will Robins,

Danger! 400

xiii

Preparing for the

Worst 400

suid and sgid

401

File and Directory

Permissions 402

Files 402

Directories 403

How suid and sgid Fit into This

Sites 408

Summary 409

21 Shell Programming 411

Creating and Executing a Shell

Program 412

Variables 413

Assigning a Value to a

Variable 414Accessing Variable

Values 414

Positional

Parameters 415

Built-in

Variables 416

Special

Characters 416

Double

Quotes 417

Single

Quote 418

Backslash 418

Backtick 419

Comparison of

Expressions 419

pdksh and bash

419

tcsh 423

Iteration

Statements 426

The for

Statement 426

The while

Statement 427

The until

Statement 428

The repeat Statement

(tcsh) 429The select Statement

(pdksh) 429The shift

Statement 429

Conditional

Statements 430

The if

Statement 430

The case

Statement 431

Miscellaneous

Statements 433

The break

Statement 433

The exit

Statement 433

Functions 434

Summary 434

Contents

Red Hat Linux, Second Edition

UNLEASHED

xiv

Part VI Automation, Programming, and

Modifying Source Code

Analysis of the

Implementation 439

Tips for Improving Automation

Technique 441

Continuing

Education 441

Good

Engineering 442

Shell

Scripts 442

chstr 442

WWW

Retrieval 443

Conclusions on Shell

Programming 445cron and at

Jobs 445

cron and find—Exploring Disk

Usage 445

at: Scheduling Future

Events 446Other Mechanisms: Expect, Perl, and

More 447

Comparing

Technologies 447

Expect 447

Perl 449

Other

Tools 449

Internal

Scripts 452

Concluding Challenge for an Automater—

Explaining Value 452

Summary 453

23 C and C++ Programming 455

Introduction to

C 456

Statement

Controls 465

Functions 468

Creating a Simple

Program 470

Building Large

Applications 472

Debugging

Tools 473

Introduction to C+

+ 474

Programming in C++: Basic

Concepts 474

File

Naming 475

Differences Between C and C+

+ 475

Scope of Reference in C and C+

GNU C/C++ Compiler Command-Line

Switches 484

Additional

Resources 485

Summary 485

24 Perl Programming 487

A Simple Perl

Program 488

Perl Variables and Data

Structures 489Conditional Statements: if/else

489

Looping 490

for 490

foreach 490

while 491

until 491

Regular

Expressions 491

Access to the

Shell 492

Command-Line

Mode 492

Automation Using

Perl 493

Moving

Files 493

Purging

Logs 495

Posting to

Usenet 496

For More

Information 496

Summary 497

25 tcl and tk Programming 499

tcl

Basics 500

Interactive Use of tcl

500Noninteractive Use of tcl

501

The tcl

Language 502

Command

Structure 502

Comments 502

Datatypes 502

Variables 503

Manipulating String

Values 506Manipulating Numeric

Values 507Quoting and

Substitution 509

Flow Control—if and

switch 511Loops 512

File I/O and File

Info 514

Procedures 516

The tk

Toolkit 517

Creating

Widgets 518

Widget

Options 519

A tcl/tk Widget Programming

Example 520

A tcl/tk Interface to

xsetroot 522Summary 527

26 Motif Programming 529

What Is

Motif? 530

Where Do I Get

Motif? 531

What Version of Motif Should I

Use? 531