Sams Teach Yourself CGI in 24 Hours, 2nd Edition ppt

www.it-ebooks.info
800 East 96th St., Indianapolis, Indiana, 46240 USA
Teach Yourself
in
24
Hours
Rafe Colburn
CGI
SECOND EDITION
00 0672324040 FM 8/28/03 9:41 AM Page i
www.it-ebooks.info
Sams Teach Yourself CGI in 24 Hours,
Second Edition
Copyright  2003 by Sams Publishing
All rights reserved. No part of this book shall be reproduced, stored in a
retrieval system, or transmitted by any means, electronic, mechanical, photo-
copying, recording, or otherwise, without written permission from the pub-
lisher. No patent liability is assumed with respect to the use of the information
contained herein. Although every precaution has been taken in the preparation
of this book, the publisher and author assume no responsibility for errors or
omissions. Nor is any liability assumed for damages resulting from the use of
the information contained herein.
International Standard Book Number: 0-672-32404-0
Library of Congress Catalog Card Number: 2002107939
Printed in the United States of America
First Printing: September 2002
05 04 03 4 3 2
Trademarks
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
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.
Warning and Disclaimer
Every effort has been made to make this book as complete and as accurate as
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.
Bulk Sales
Sams Publishing offers excellent discounts on this book when ordered in quan-
tity for bulk purchases or special sales. For more information, please contact
U.S. Corporate and Government Sales
1-800-382-3419

For sales outside of the U.S., please contact
International Sales
1-317-428-3341

ACQUISITIONS EDITOR
Betsy Brown
DEVELOPMENT EDITOR
Scott Meyers
MANAGING EDITOR
Charlotte Clapp
INDEXER
Kelly Castell
PROOFREADER
Suzanne Thomas
TECHNICAL EDITORS
Greg Perry
J. Eric Sloan

TEAM COORDINATOR
Amy Patton
MULTIMEDIA DEVELOPER
Dan Scherf
INTERIOR DESIGNER
Gary Adair
COVER DESIGNER
Alan Clements
PAGE LAYOUT
Brad Lenser
00 0672324040 FM 8/28/03 9:41 AM Page ii
www.it-ebooks.info
Contents at a Glance
Introduction 1
Part I An Introduction to CGI 3
Hour 1 Overview of CGI Programming 5
2 Setting Up Your CGI Environment 19
3Downloading, Installing, and Debugging CGI Scripts 35
4Writing Your First CGI Program 53
Part II Capturing User Input 71
Hour 5 Creating HTML Forms 73
6Working with HTTP 91
7Validating User Input 111
8Creating an Email Feedback Form 131
Part III CGI Programming Languages and Tools 147
Hour 9 Web Application Architecture 149
10 Delving Further into Perl 169
11 Other Popular CGI Programming Languages 189
12 Pros and Cons of Alternate Technologies 211
Part IV Building Basic CGI Applications 227

Hour 13 Using Flat Files for Data Storage 229
14 Creating a CGI-Based Message Board 253
15 Session Management 275
16 Building a Simple Shopping Cart 299
17 Content Management with CGI 321
Part V Integrating Databases with CGI 339
Hour 18 Working with Relational Databases 341
19 How to Use the Structured Query Language 355
20 Creating an Online Store 373
00 0672324040 FM 8/26/02 11:04 AM Page iii
www.it-ebooks.info
Part VI Additional CGI Tips and Tricks 395
Hour 21 Handling Other Content Types 397
22 Securing CGI Scripts 411
23 Creating Custom Error Documents 425
24 Server Side Includes 443
Part VII Appendixes 461
Appendix A MIME Types 463
B Response Codes and Reason Phrases 467
CEnvironment Variables and Request Headers 471
D Summary of Regular Expressions 479
E ASCII Table 483
Index 489
00 0672324040 FM 8/26/02 11:04 AM Page iv
www.it-ebooks.info
Contents
Introduction 1
Part I An Introduction to CGI 3
Hour 1 Overview of CGI Programming 5
Types of Web Applications 6

A History of CGI 6
What Is a CGI Program? 7
How CGI Programs Work 8
How Resources Are Requested 8
Fulfilling the Request 9
Passing Data to a CGI Program 11
Pros and Cons of CGI 11
CGI Programming Languages 13
Perl 13
UNIX Shell 13
The C Language 14
Visual Basic 15
Python 15
Java 16
Summary 16
Q&A 16
Workshop 17
Quiz 17
Quiz Answers 17
2 Setting Up Your CGI Environment 19
The Web Server Itself 19
Hosting Your CGI Scripts 20
Running Your Own Web Server 20
Web Hosting 21
Web-Server Operating Systems 22
UNIX 22
Windows 23
The CGI Environment 23
Web Servers 24
Web-Server Directory Structure 24

How Scripts Are Executed 25
Setting Up Your CGI Development Environment 26
Step 1: Download a Web Server 26
Step 2: Install the Web Server 27
00 0672324040 FM 8/26/02 11:04 AM Page v
www.it-ebooks.info
Step 3: Download a Perl Interpreter 28
Step 4: Install the Perl Interpreter 28
Step 5: Get the Web Server Up and Running 29
Step 6: Test the Web Server 29
Step 7: Test a Perl CGI Script 30
What If Something Went Wrong? 32
Summary 33
Q&A 33
Workshop 34
Quiz 34
Exercises 34
Quiz Answers 34
3 Downloading, Installing, and Debugging CGI Scripts 35
Downloading Scripts from the Internet 36
Finding the Scripts You Need 36
What to Look for in Publicly-Available Scripts 37
Installing a Downloaded Script 38
Example: Downloading and Installing a Guestbook Script 38
Configuring the Script 39
Installing the Files and Setting Permissions 40
Testing the Script 41
Customizing the Look and Feel 41
Debugging CGI Scripts 42
Finding the Source of an Error 42

Fixing Setup Errors 44
Tools and Techniques for Debugging Your Program Code 47
Compiled Versus Interpreted Languages 48
Running CGI Scripts from the Command Line 49
Using Print Statements for Debugging 50
Summary 50
Q&A 51
Workshop 51
Quiz 51
Exercises 52
Quiz Answers 52
4Writing Your First CGI Program 53
Parts of CGI Programs 54
A Sample CGI Program 54
A URL-Redirection Program 57
How File Redirection Works 59
Pipes 60
vi Sams Teach Yourself CGI in 24 Hours
00 0672324040 FM 8/26/02 11:04 AM Page vi
www.it-ebooks.info
Working with Files in Perl 61
Common Statements Used in Perl 63
The if Statement 65
Perl Expressions 66
Summary 68
Q&A 68
Workshop 69
Quiz 69
Exercises 69
Quiz Answers 69

Part II Capturing User Input 71
5Creating HTML Forms 73
The
<form> Tag 74
The
action Attribute 74
The
method Attribute 75
The
enctype Attribute 75
The
target Attribute 75
The
<input> Tag 76
Text Input Fields 76
Password Fields 77
Check Boxes 78
Radio Buttons 78
Hidden Fields 79
File Upload Fields 80
Reset Buttons 80
Submit Buttons 80
Using Images as Submit Buttons 81
Other Form Fields 82
Text Areas 83
Select Lists 84
Workshop: Building an Entire Form 85
Elements in the Survey Form 87
Summary 87
Q&A 88

Workshop 88
Quiz 88
Exercises 88
Quiz Answers 89
Contents vii
00 0672324040 FM 8/26/02 11:04 AM Page vii
www.it-ebooks.info
6Working with HTTP 91
HTTP Basics 92
What Takes Place During an HTTP Session 92
Step 1: Establish a TCP Connection 93
Step 2: The Web Browser Sends a Command to the Server 94
Step 3: The Web Browser Sends Request Headers 95
Step 4: The Web Server Responds 95
Step 5: The Web Server Sends Response Headers 96
Step 6: The Web Server Sends the Data to the Browser 96
Step 7: The Web Server Closes the TCP Connection 96
Request Methods 97
The
GET Method 97
The
POST Method 98
Choosing Between
GET and POST 98
Server Response Codes 99
Response Headers 101
Cache-control 101
Content-length 101
Content-type 101
Expires 101

Pragma 102
Server 102
Set-Cookie 102
NPH Scripts 102
Content Types 103
How Servers Use Content Types 104
Content-Type Categories 105
Nonstandard Types 106
Secure Connections 107
Summary 108
Q&A 109
Workshop 109
Quiz 109
Exercises 109
Quiz Answers 110
7Validating User Input 111
Using JavaScript for Form Validation 111
How JavaScript Works to Validate Forms 112
An Example of Form Validation 113
The Form Itself 113
The Event Handler 114
Designing Easily Validated Forms 114
viii Sams Teach Yourself CGI in 24 Hours
00 0672324040 FM 8/26/02 11:04 AM Page viii
www.it-ebooks.info
Incorporating Validation into the Form-Processing Code 115
How a Form-Processing Program Works 115
An Example of Form Processing 116
The Main Script Logic 117
The Input Validation Subroutine 118

The Output Subroutine 119
The Form Creation Subroutine 120
The Full Source Code 121
Validating Values 123
Regular Expressions 124
An Example That Uses Regular Expressions 126
Summary 128
Q&A 128
Workshop 128
Quiz 128
Exercises 129
Quiz Answers 129
8Creating an Email Feedback Form 131
What Kinds of Applications Involve Sending Email? 132
How Email Works 132
Mail Message Composition 134
Using
Net::SMTP 135
Example: Sending Email from a CGI Script 136
Setting Things Up 138
The Application Logic 139
Validating the Form 140
Sending the Email Message 141
Using
sendmail 141
Using
sendmail with Perl 142
Summary 143
Q&A 144
Workshop 144

Quiz 145
Exercises 145
Quiz Answers 145
Part III CGI Programming Languages and Tools 147
9Web Application Architecture 149
Application Design 150
Round-trip Scripts 150
Figuring Out Whether a Form Was Submitted 151
Declarative Programming 152
Contents ix
00 0672324040 FM 8/26/02 11:04 AM Page ix
www.it-ebooks.info
Handling Many Types of Requests 153
Sharing Code Among Scripts 156
Using
CGI::Application 158
Installing
CGI::Appliction 159
Creating
CGI::Application Applications 162
An Example That Uses
CGI::Application 162
Other
CGI::Application Notes 166
Summary 166
Workshop 167
Q&A 167
Quiz 167
Exercises 167
Quiz Answers 168

10 Delving Further into Perl 169
CGI.pm 169
Accessing
CGI.pm from Your Program 170
Decoding Form Data via
CGI.pm 171
Named Image-Input Fields 171
Multiple Select Lists 172
File Upload Fields 172
Generating HTTP Headers and HTML Tags via
CGI.pm 175
How to Generate HTTP Headers 176
How to Generate HTML Tags 177
Skipping the Object-Oriented Stuff 179
cgi-lib.pl 180
Replacing
cgi-lib.pl with CGI.pm 180
Handling Errors with
CGI::Carp 181
Sending Fatal Errors to the Browser 182
Resources for Perl Programmers 182
Perl Documentation 183
Perl Information on the Web 183
Perl Books 184
The Comprehensive Perl Archive Network 184
Summary 186
Q&A 186
Workshop 186
Quiz 186
Exercises 186

Quiz Answers 187
x Sams Teach Yourself CGI in 24 Hours
00 0672324040 FM 8/26/02 11:04 AM Page x
www.it-ebooks.info
11 Other Popular CGI Programming Languages 189
Will My Favorite Language Work for CGI? 189
Writing CGI Programs Using the Bourne Shell 190
How Shell Scripts Work 191
Creating Gateways to UNIX Commands 192
Working with Query Strings 193
Writing a Program That Uses the Query String 194
Writing CGI Programs in C 195
The
cgic Library 196
Printing Headers 196
Printing Output 197
Handling Form Input 197
A C Example 201
Writing CGI Programs in Python 205
A Python Example 206
Summary 208
Q&A 208
Workshop 209
Quiz 209
Quiz Answers 209
12 Pros and Cons of Alternate Technologies 211
Looking Back 212
Why CGI Alternatives Appeared 212
Getting Past CGI’s Limitations 212
J2EE 213

Servlets 214
JavaServer Pages 214
PHP 216
Examples Using PHP 216
ASP.NET 218
Business Objects 218
Code Blocks 219
HTML Pages 221
Macromedia ColdFusion 221
ColdFusion Sample Code 221
The Apache
mod_perl Module 222
Porting Your Scripts from CGI to
mod_perl 223
Summary 224
Q&A 224
Workshop 225
Quiz 225
Exercises 225
Quiz Answers 225
Contents xi
00 0672324040 FM 8/26/02 11:04 AM Page xi
www.it-ebooks.info
Part IV Building Basic CGI Applications 227
13 Using Flat Files for Data Storage 229
What Is a Database? 230
Flat-File Databases 230
Delimiting Data Using Characters 231
Delimiting Data Using Field Widths 231
File Operations 232

Retrieving Records from a Database 232
Inserting a Record into a Database 232
Deleting Records from a Database 232
Modifying a Record in a Database 233
File Locking 233
Building a Database Application 234
The Sample Database 234
Retrieving Records from the Database 235
Inserting a Record into the Database 238
Deleting Records from the Database 243
Modifying a Record in the Database 245
Summary 250
Q&A 250
Workshop 250
Quiz 251
Exercises 251
Quiz Answers 251
14 Creating a CGI-Based Message Board 253
The Structure of the Application 254
The File Format 254
The Display Script 255
Utility Subroutines 260
Opening the Topic File 260
Parsing a Topic File 261
Printing the Topic List 263
Printing a Topic 264
The Posting Script 265
Presenting the New Topic Form 270
Processing a New Topic Submission 271
Adding a Response 272

Summary 272
Q&A 273
xii Sams Teach Yourself CGI in 24 Hours
00 0672324040 FM 8/26/02 11:04 AM Page xii
www.it-ebooks.info
Workshop 273
Quiz 273
Exercises 273
Quiz Answers 273
15 Session Management 275
Why Use Session Management? 276
Basic Authentication 277
Hidden Fields in Forms 278
Hidden Form Fields Example 279
Application Logic 281
Printing the Hidden Fields 281
Using Cookies 282
How Cookies Work 283
Using Cookies to Save User Information 285
Using Cookies to Retrieve User Information 287
Setting and Retrieving Cookies with JavaScript 289
Session Management with Cookies 290
The Catalog Page 291
The Checkout Form 293
Why CGI and Cookies Don’t Mix 295
Summary 295
Q&A 296
Workshop 296
Quiz 296
Exercises 297

Quiz Answers 297
16 Building a Simple Shopping Cart 299
How the Sample Shopping Cart Works 300
The Catalog 301
Printing the Catalog 304
Adding Items to the Shopping Cart 305
The Contents of the Shopping Cart 306
Printing the User’s Cart 309
Removing an Item from the Cart 311
Checkout 312
The Checkout Script for This Example 313
Summary 318
Q&A 319
Workshop 319
Quiz 320
Exercises 320
Quiz Answers 320
Contents xiii
00 0672324040 FM 8/26/02 11:04 AM Page xiii
www.it-ebooks.info
17 Content Management with CGI 321
Why Content Publishing? 321
Separating Content and Presentation 322
Building in an Editorial Process 322
Types of Content Publishing Systems 322
Data Storage for Content Publishing Systems 324
A Content Publishing Example 324
The Story-Input Program 325
The Story-Display Program 330
Free Content Management Systems 335

Mason 336
Zope 337
PostNuke 337
Red Hat Content Management Solution 337
Summary 337
Q&A 337
Workshop 338
Quiz 338
Exercises 338
Quiz Answers 338
Part V Integrating Databases with CGI 339
18 Working with Relational Databases 341
The Relational Database Model 341
Structured Query Language 343
Statements for Data Manipulation 343
Statements for Data Definition 344
Statements for Database Administration 345
Database Design 345
Characteristics of Good Databases 346
Symptoms of Bad Databases 347
The Design Process 347
Creating a Database 348
Choosing Which Database to Access 349
Creating a Table 349
Relational Data Types 350
String Data 351
Numeric Data 352
Temporal Data 352
Summary 353
Q&A 353

xiv Sams Teach Yourself CGI in 24 Hours
00 0672324040 FM 8/26/02 11:04 AM Page xiv
www.it-ebooks.info
Workshop 353
Quiz 353
Exercises 354
Quiz Answers 354
19 How to Use the Structured Query Language 355
Structured Query Language 356
The
SELECT Statement 357
Adding, Deleting, and Modifying Records 363
Database Interfaces 365
ODBC 366
DBI and DBD 366
A Sample Program Using DBI and DBD 367
Summary 370
Q&A 370
Workshop 371
Quiz 371
Exercises 371
Quiz Answers 371
20 Creating an Online Store 373
The Database Design 373
The Catalog Script 377
Opening and Closing Database Connections 381
Displaying the Product List 381
Adding Items to the Shopping Cart 382
The Shopping Cart Script 382
Displaying the Shopping Cart 385

Removing Items from the Shopping Cart 386
The Checkout Script 387
Storing Orders in the Database 392
Summary 393
Q&A 393
Workshop 394
Quiz 394
Exercises 394
Quiz Answers 394
Part VI Additional CGI Tips and Tricks 395
21 Handling Other Content Types 397
Content Types 397
Handling Binary Content 398
An Authenticated Download Application 399
Contents xv
00 0672324040 FM 8/26/02 11:04 AM Page xv
www.it-ebooks.info
Creating Your Own Ad Server 403
Tracking User Activity 405
Summary 409
Q&A 409
Workshop 409
Quiz 409
Exercises 410
Quiz Answers 410
22 Securing CGI Scripts 411
Why Security? 412
The Crack-a-Mac Contest 412
Risk Assessment 413
Securing Your Web Server 414

Keep Your Software Up-to-Date 415
Store Your CGI Scripts Together 415
File Permissions 416
Server Options That Are Bad for Security 417
Common CGI Security Holes 417
A Note on How CGI Works 417
The Buffer Overflow Problem 418
Don’t Send Raw Input to Shell Commands 419
Using File Paths Is Risky 420
Don’t Place the Perl Interpreter in cgi-bin 421
Security Hole with DOS Batch Files 421
Keep Your Server Information Private 421
Safe Programming 422
Running Shell Commands Without Using the Shell 422
Summary 423
Q&A 423
Workshop 424
Quiz 424
Exercises 424
Quiz Answers 424
23 Creating Custom Error Documents 425
What Is an Error Document? 425
Configuring Your Web Server for Custom Error Documents 427
The Apache Web Server 428
Using HTML to Create a Basic Error Document 429
xvi Sams Teach Yourself CGI in 24 Hours
00 0672324040 FM 8/26/02 11:04 AM Page xvi
www.it-ebooks.info
Using CGI to Create an Advanced Error Document 430
Environment Variables for Error Documents 430

Linking Back from the Error Document to the Referring Page 431
Creating Custom Links from the Error Document 432
Handling a “Not Found” Error 435
Handling an “Unauthorized” Error 439
Summary 440
Q&A 440
Workshop 441
Quiz 441
Exercises 441
Quiz Answers 441
24 Server Side Includes 443
How Server Side Includes Work 444
Setting Up Your Web Server for SSI 444
Apache 445
Microsoft Internet Information Server 446
Using SSI Directives 446
flastmod 446
SSI Directives 448
#echo 448
#include 448
#fsize 449
#exec 449
#config 450
Designing Pages Using SSI 453
Using the
#include Directive 453
Last Modified Dates 455
Using the
#exec Directive 455
XSSI 457

printenv 457
set 457
if Directives 457
Summary 459
Q&A 459
Workshop 459
Quiz 460
Exercises 460
Quiz Answers 460
Contents xvii
00 0672324040 FM 8/26/02 11:04 AM Page xvii
www.it-ebooks.info
Part VII Appendixes 461
AMIME Types 463
B Response Codes and Reason Phrases 467
C Environment Variables and Request Headers 471
D Summary of Regular Expressions 479
E ASCII Tables 483
Index 489
00 0672324040 FM 8/26/02 11:04 AM Page xviii
www.it-ebooks.info
About the Author
Rafe Colburn is a software developer who works at TogetherSoft in Raleigh, North
Carolina. He’s also the author of Special Edition Using SQL for Que Publishing and has
contributed to a number of other computer books. His personal site, rc3.org Daily, can be
found at , and he can be reached via email at
00 0672324040 FM 8/26/02 11:04 AM Page xix
www.it-ebooks.info
Dedication
For Patricia

Acknowledgments
There are always too many contributors to any large effort to do an adequate job of
thanking them in a space like this one. First of all, I’d like to thank the readers of my
previous CGI book who took time to send comments, both positive and negative.
Secondly, I’d like to thank the editorial team that helped to produce this book. Betsy
Brown, Scott Meyers, Amy Patton, and J. Eric Slone are all deserving of praise, along
with the other people at Sams who did a great job in facilitating the writing of this book.
And, saving the best for last, I’d like to thank my wife for her patience and her support.
00 0672324040 FM 8/26/02 11:04 AM Page xx
www.it-ebooks.info
We Want to Hear from You!
As the reader of this book, you are our most important critic and commentator. We value
your opinion and want to know what we’re doing right, what we could do better, what
areas you’d like to see us publish in, and any other words of wisdom you’re willing to
pass our way.
You can email or write me directly to let me know what you did or didn’t like about this
book—as well as what we can do to make our books stronger.
Please note that I cannot help you with technical problems related to the topic of this
book, and that due to the high volume of mail I receive, I might not be able to reply to
every message.
When you write, please be sure to include this book’s title and author as well as your
name and phone or email address. I will carefully review your comments and share them
with the author and editors who worked on the book.
Email:
Mail: Mark Taber
Associate Publisher
Sams Publishing
800 East 96th Street
Indianapolis, IN 46240 USA
Reader Services

For more information about this book or others from Sams Publishing, visit our Web site
at www.samspublishing.com. Type the ISBN (excluding hyphens) or the title of the book
in the Search box to find the book you’re looking for.
00 0672324040 FM 8/28/03 9:41 AM Page xxi
www.it-ebooks.info
00 0672324040 FM 8/26/02 11:04 AM Page xxii
www.it-ebooks.info
Introduction
During the past few years, Web applications have undergone an amazing transition. Not
that long ago they were a relative rarity. Sites might have an email feedback form, or a
search engine, or maybe even a message board. From there, we moved to a realm in
which hundreds of companies centered around Web applications sprung up. Since then,
the craze has died down some and many of those companies are no longer around, but
Web applications themselves aren’t going away—indeed, they’re more common than
ever.
These days, not only does nearly every company have a Web site, but most of them fea-
ture Web applications as well. Corporate intranets are also filled with Web applications
of all kinds. More importantly, most software companies offer some level of Web inte-
gration for their software. Large enterprise software companies like Siebel, SAP, and
Oracle have Web interfaces for their products. The main reason that Web applications
aren’t in the headlines every day any more is that they’ve become so common.
The primary focus of this book is on using the Common Gateway Interface (CGI), which
is built into nearly every Web server, to develop Web applications. The biggest advantage
of CGI is that it supports nearly every popular programming language. So, if you already
know how to program, you can probably get started writing Web applications right away.
Even if you don’t program, you can copy existing CGI programs and modify them to suit
your own needs.
The larger focus of this book is on teaching you how Web applications are designed and
built. Although you may start out writing CGI programs, there’s a good chance that down
the road you’ll be building applications using some other platform, like Active Server

Pages, ColdFusion, or perhaps Java servlets. Even so, this book will provide you with the
knowledge you need to understand how Web applications work in general, and some
methods you can use to write Web applications that are easy to improve and maintain.
Also, knowing CGI will enable you to quickly solve problems that you might not be able
to solve using other technologies. For example, because CGI programs can be written in
a wide variety of languages, often it’s easiest to write Web applications that communicate
with other programs using CGI.
I should also point out that most of the examples in this book are written in Perl. Perl is a
scripting language that’s available for most computing platforms, including Unix and
Windows. It has a number of features that make it well-suited to CGI programming, and
in fact, it’s the most popular language for writing CGI programs. The biggest advantage
for readers of this book is that it’s easy to learn Perl in bits and pieces. You don’t need to
understand any big concepts behind software design in order to write useful programs in
Perl.
01 0672324040 Intro 8/26/02 11:04 AM Page 1
www.it-ebooks.info
My goal in this book is to explain the Perl concepts that I use in the example programs,
and not to go beyond that. I also used as few special Perl features as possible in order to
apply the lessons in these examples to the programming language that you use to write
CGI programs. If you don’t know any programming languages, Perl is as good a starting
point as any other language. I’d advise you to pick up a Perl book (like Laura Lemay’s
Teach Yourself Perl in 21 Days), or at least check out the Perl information at
www.perl.com.
Hopefully this book will be the first step in sending you off on a long and successful
career as a professional or amateur developer of Web applications. If you have any com-
ments or feedback, please send them to me at Good luck!
2 Sams Teach Yourself CGI in 24 Hours
01 0672324040 Intro 8/26/02 11:04 AM Page 2
www.it-ebooks.info