Perl by Example (4th Edition) (By Example)

This tutorial/reference is the ideal guide for UNIX professionals who want to (or must) learn Perl (Practical Extraction and Report Language) as quickly as possible. The author teaches Perl through extensive use of thoroughly annotated programming examples, and through comparing and contrasting the features of Perl with those of the UNIX shells and C programming language. Cover......Page 1 Contents......Page 8 Preface......Page 28 1.1 What Is Perl?......Page 32 1.2 What Is an Interpreted Language?......Page 33 1.3.1 Which Perl?......Page 34 1.3.2 What Is Perl 6?......Page 35 1.4 Where to Get Perl......Page 36 1.4.1 What Version Do I Have?......Page 38 1.5 What Is CPAN?......Page 40 1.6.1 Perl Man Pages......Page 41 1.6.2 HTML Documentation......Page 42 1.8 What's Next?......Page 43 2.1.2 A Note to Non-Programmers......Page 44 2.1.3 Perl Syntax and Constructs......Page 45 2.3 What's Next?......Page 60 3.1 Script Setup......Page 62 3.2.1 Startup......Page 63 3.2.4 Statements, Whitespace, and Linebreaks......Page 65 3.2.6 Perl Statements......Page 66 3.2.8 Executing the Script......Page 67 3.2.9 Sample Script......Page 68 3.2.10 What Kinds of Errors to Expect......Page 69 3.3 Perl at the Command Line......Page 70 3.3.2 The -n Switch......Page 71 3.3.3 The -c Switch......Page 73 3.5 What's Next?......Page 74 EXERCISE 3 Getting with It Syntactically......Page 75 4.2 Words......Page 76 4.3 The print Function......Page 77 4.3.1 Quotes......Page 78 4.3.2 Literals (Constants)......Page 80 4.3.3 Printing Literals......Page 82 4.3.4 The warnings Pragma and the -w Switch......Page 86 4.3.5 The diagnostics Pragma......Page 88 4.3.6 The strict Pragma and Words......Page 89 4.4 The printf Function......Page 90 4.4.1 The sprintf Function......Page 93 4.4.2 Printing without Quotes—The here document......Page 94 4.6 What's Next?......Page 97 EXERCISE 4 A String of Perls......Page 98 5.1.2 Scope and the Package......Page 100 5.1.3 Naming Conventions......Page 101 5.1.4 Assignment Statements......Page 102 5.1.5 Quoting Rules......Page 103 5.2.1 Scalar Variables......Page 108 5.2.2 Arrays......Page 111 5.2.3 Hashes......Page 118 5.2.4 Complex Data Structures......Page 122 5.3.1 Assigning Input to a Scalar Variable......Page 125 5.3.2 The chop and chomp Functions......Page 126 5.3.3 The read Function......Page 127 5.3.4 The getc Function......Page 128 5.3.5 Assigning Input to an Array......Page 129 5.3.6 Assigning Input to a Hash......Page 130 5.4.1 The chop and chomp Functions (with Lists)......Page 131 5.4.3 The delete Function......Page 132 5.4.5 The join Function......Page 133 5.4.6 The map Function......Page 134 5.4.7 The pack and unpack Functions......Page 136 5.4.8 The pop Function......Page 138 5.4.10 The shift Function......Page 139 5.4.11 The splice Function......Page 140 5.4.12 The split Function......Page 141 5.4.13 The sort Function......Page 145 5.4.14 The reverse Function......Page 147 5.4.15 The unshift Function......Page 148 5.5.1 The keys Function......Page 149 5.5.3 The each Function......Page 150 5.5.4 Sorting a Hash......Page 151 5.5.5 The delete Function......Page 157 5.5.6 The exists Function......Page 158 5.6.1 Loading a Hash from a File......Page 159 5.6.2 Special Hashes......Page 160 5.6.3 Context......Page 162 5.7 What You Should Know......Page 163 5.8 What's Next?......Page 164 EXERCISE 5 The Funny Characters......Page 165 6.1 About Perl Operators......Page 168 6.2 Mixing Data Types......Page 169 6.3 Precedence and Associativity......Page 170 6.3.1 Assignment Operators......Page 172 6.3.2 Relational Operators......Page 174 6.3.3 Equality Operators......Page 177 6.3.4 Logical Operators (Short-Circuit Operators)......Page 180 6.3.5 Logical Word Operators......Page 182 6.3.6 Arithmetic Operators......Page 184 6.3.7 Autoincrement and Autodecrement Operators......Page 185 6.3.8 Bitwise Logical Operators......Page 187 6.3.9 Conditional Operators......Page 190 6.3.10 Range Operator......Page 192 6.3.11 Special String Operators and Functions......Page 193 6.3.12 Arithmetic Functions......Page 195 6.5 What's Next?......Page 199 EXERCISE 6 Operator, Operator......Page 200 7.1 Control Structures, Blocks, and Compound Statements......Page 202 7.1.1 Decision Making—Conditional Constructs......Page 203 7.2.1 The while Loop......Page 208 7.2.2 The until Loop......Page 210 7.2.3 The for Loop......Page 213 7.2.4 The foreach Loop......Page 215 7.2.5 Loop Control......Page 219 7.2.6 The switch Statement......Page 227 7.4 What's Next?......Page 231 EXERCISE 7 What Are Your Conditions?......Page 232 8.1 What Is a Regular Expression?......Page 234 8.2.1 Conditional Modifiers......Page 235 8.2.2 The DATA Filehandle......Page 236 8.2.3 Looping Modifiers......Page 240 8.3.1 The m Operator and Matching......Page 241 8.3.2 The s Operator and Substitution......Page 247 8.3.3 Pattern Binding Operators......Page 257 8.5 What's Next?......Page 263 EXERCISE 8 A Match Made in Heaven......Page 265 9.1 Regular Expression Metacharacters......Page 266 9.1.1 Metacharacters for Single Characters......Page 269 9.1.2 Whitespace Metacharacters......Page 278 9.1.3 Metacharacters to Repeat Pattern Matches......Page 281 9.1.4 The tr or y Function......Page 307 9.2.1 Perl and Unicode......Page 312 9.4 What's Next?......Page 314 EXERCISE 9 And the Search Goes On.........Page 315 10.1.1 Opening Files—The open Function......Page 316 10.1.2 Open for Reading......Page 317 10.1.3 Open for Writing......Page 322 10.1.4 Win32 Binary Files......Page 323 10.1.5 Open for Appending......Page 324 10.1.6 The select Function......Page 325 10.1.7 File Locking with flock......Page 326 10.1.8 The seek and tell Functions......Page 327 10.1.9 Open for Reading and Writing......Page 332 10.1.10 Open for Pipes......Page 333 10.2.1 The ARGV Array......Page 341 10.2.2 ARGV and the Null Filehandle......Page 342 10.2.3 The eof Function......Page 346 10.2.4 The -i Switch—Editing Files in Place......Page 348 10.3 File Testing......Page 350 10.4 What You Should Know......Page 352 10.5 What's Next?......Page 353 EXERCISE 10 Getting a Handle on Things......Page 354 11.1 Subroutines/Functions......Page 356 11.1.1 Defining and Calling a Subroutine......Page 357 11.2 Passing Arguments......Page 361 11.2.1 Prototypes......Page 369 11.2.2 Return Value......Page 371 11.2.3 Context and Subroutines......Page 373 11.3.1 Symbolic References—Typeglobs......Page 375 11.3.2 Hard References—Pointers......Page 380 11.3.3 Autoloading......Page 385 11.3.4 BEGIN and END Subroutines (Startup and Finish)......Page 388 11.4 What You Should Know......Page 389 11.5 What's Next?......Page 390 EXERCISE 11 I Can't Seem to Function without Subroutines......Page 391 12.1.2 An Analogy......Page 394 12.1.3 Definition......Page 395 12.1.4 The Symbol Table......Page 396 12.2 The Standard Perl Library......Page 401 12.2.1 The @INC Array......Page 402 12.2.2 Packages and .pl Files......Page 405 12.2.3 Modules and .pm Files......Page 409 12.2.4 Exporting and Importing......Page 410 12.2.5 How to "use" a Module from the Standard Perl Library......Page 416 12.2.6 Using Perl to Create Your Own Module......Page 419 12.3 Modules from CPAN......Page 421 12.3.1 Using PPM......Page 424 12.5 What's Next?......Page 429 EXERCISE 12 I Hid All My Perls in a Package......Page 430 13.1.1 Symbolic versus Hard References......Page 432 13.1.2 Hard References, Pointers......Page 434 13.1.3 References and Anonymous Variables......Page 437 13.1.4 Nested Data Structures......Page 439 13.1.5 References and Subroutines......Page 445 13.1.6 Filehandle References......Page 448 13.1.7 The ref Function......Page 449 13.3 What's Next?......Page 451 EXERCISE 13 It's Not Polite to Point!......Page 452 14.1.1 Packages and Modules Revisited......Page 454 14.1.2 Some Object-Oriented Lingo......Page 455 14.2.1 Real World......Page 456 14.2.3 Classes and Privacy......Page 457 14.2.4 Objects......Page 459 14.2.5 The bless Function......Page 460 14.2.6 Methods......Page 462 14.2.7 What an Object-Oriented Module Looks Like......Page 464 14.2.8 Polymorphism and Dynamic Binding......Page 476 14.2.9 Destructors and Garbage Collection......Page 482 14.3.1 What Is a Closure?......Page 484 14.3.2 Closures and Objects......Page 486 14.4.1 The @ISA Array and Calling Methods......Page 491 14.4.2 $AUTOLOAD, sub AUTOLOAD, and UNIVERSAL......Page 493 14.4.3 Derived Classes......Page 496 14.4.5 Overriding a Parent Method......Page 502 14.5.1 pod Files......Page 505 14.5.2 pod Commands......Page 507 14.5.4 Translating pod Documentation into Text......Page 508 14.6.1 Another Look at the Standard Perl Library......Page 510 14.6.2 An Object-Oriented Module from the Standard Perl Library......Page 512 14.6.3 Using a Module with Objects from the Standard Perl Library......Page 514 14.7 What You Should Know......Page 515 14.8 What's Next?......Page 516 EXERCISE 14 What's the Object of This Lesson?......Page 517 15.1.1 The tie Function......Page 524 15.1.3 Tying a Scalar......Page 525 15.1.4 Tying an Array......Page 528 15.1.5 Tying a Hash......Page 531 15.2 DBM Files......Page 536 15.2.1 Creating and Assigning Data to a DBM File......Page 537 15.2.2 Retrieving Data from a DBM File......Page 539 15.2.3 Deleting Entries from a DBM File......Page 541 15.4 What's Next?......Page 543 16.1 Static and Dynamic Web Pages......Page 544 16.2.1 Internet Communication between Client and Server......Page 547 16.3 Creating a Web Page with HTML......Page 553 16.4 How HTML and CGI Work Together......Page 557 16.4.1 A Simple CGI Script......Page 558 16.4.2 Error Log Files......Page 561 16.5.1 CGI Environment Variables......Page 562 16.6 CGI and Forms......Page 566 16.6.1 Input Types for Forms......Page 567 16.6.2 Creating an HTML Form......Page 568 16.6.3 The GET Method......Page 572 16.6.4 Processing the Encoded Data......Page 575 16.6.5 Putting It All Together......Page 579 16.6.6 The POST Method......Page 582 16.6.7 Handling E-mail......Page 586 16.7.1 Introduction......Page 590 16.7.3 Two Styles of Programming with CGI.pm......Page 591 16.7.4 An Important Warning!......Page 593 16.7.5 HTML Form Methods......Page 595 16.7.6 How CGI.pm Works with Forms......Page 603 16.7.7 CGI.pm Form Elements......Page 608 16.7.8 Methods Defined for Generating Form Input Fields......Page 610 16.7.9 Error Handling......Page 624 16.7.10 HTTP Header Methods......Page 627 EXERCISE 16 Surfing for Perls......Page 630 17.1 Introduction......Page 634 17.2.1 Client/Server Databases......Page 635 17.2.2 Components of a Relational Database......Page 636 17.2.3 Talking to the Database with SQL (the Structured Query Language)......Page 641 17.3.2 Installing MySQL......Page 644 17.3.3 Connecting to MySQL......Page 645 17.3.4 Graphical User Tools......Page 647 17.3.5 Finding the Databases......Page 650 17.3.6 Getting Started with Basic Commands......Page 652 17.4 What Is the Perl DBI?......Page 669 17.4.1 Installing the DBI......Page 670 17.4.2 The DBI Class Methods......Page 676 17.4.3 How to Use DBI......Page 678 17.4.4 Connecting to and Disconnecting from the Database......Page 679 17.4.6 Preparing a Statement Handle and Fetching Results......Page 681 17.4.7 Handling Quotes......Page 685 17.4.8 Getting Error Messages......Page 686 17.5.1 The do() method......Page 697 17.6 Transactions......Page 701 17.7 Using CGI and the DBI to Select and Display Entries......Page 703 17.8 What's Left?......Page 709 17.10 What's Next?......Page 710 EXERCISE 17 Select * from Chapter......Page 711 18.1 System Calls......Page 716 18.1.1 Directories and Files......Page 718 18.1.2 Directory and File Attributes......Page 720 18.1.3 Finding Directories and Files......Page 723 18.1.4 Creating a Directory—The mkdir Function......Page 726 18.1.5 Removing a Directory—The rmdir Function......Page 727 18.1.6 Changing Directories—The chdir Function......Page 728 18.1.7 Accessing a Directory via the Directory Filehandle......Page 729 18.1.8 Permissions and Ownership......Page 732 18.1.9 Hard and Soft Links......Page 736 18.1.10 Renaming Files......Page 739 18.1.11 Changing Access and Modification Times......Page 740 18.1.12 File Statistics......Page 741 18.1.13 Low-Level File I/O......Page 743 18.1.14 Packing and Unpacking Data......Page 746 18.2.1 UNIX Processes......Page 752 18.2.3 The Environment (UNIX and Windows)......Page 754 18.2.4 Processes and Filehandles......Page 756 18.2.5 Process Priorities and Niceness......Page 759 18.2.6 Password Information......Page 761 18.2.7 Time and Processes......Page 765 18.2.8 Process Creation UNIX......Page 770 18.2.9 Process Creation Win32......Page 775 18.3.1 The syscall Function and the h2ph Script......Page 778 18.3.2 Command Substitution—The Backquotes......Page 779 18.3.3 The Shell.pm Module......Page 780 18.3.4 The system Function......Page 781 18.3.5 here documents......Page 783 18.3.6 Globbing (Filename Expansion and Wildcards)......Page 784 18.4.1 The die Function......Page 786 18.4.3 The eval Function......Page 788 18.5 Signals......Page 791 18.6 What You Should Know......Page 795 18.7 What's Next?......Page 796 19.1.1 Steps in Defining the Template......Page 798 19.1.2 Changing the Filehandle......Page 801 19.1.3 Top-of-the-Page Formatting......Page 802 19.1.4 The select Function......Page 807 19.1.5 Multiline Fields......Page 809 19.1.6 Filling Fields......Page 810 19.1.7 Dynamic Report Writing......Page 812 19.3 What's Next?......Page 814 EXERCISE 19 Pretty as a Picture!......Page 815 20.3 Network Protocols (TCP/IP)......Page 816 20.3.4 User Datagram Protocol (UDP)......Page 817 20.4.3 Port Numbers......Page 818 20.4.4 Perl Protocol Functions......Page 819 20.4.5 Perl's Server Functions......Page 821 20.4.6 Perl's Host Information Functions......Page 823 20.5 Sockets......Page 825 20.5.2 Socket Domains......Page 826 20.5.3 Creating a Socket......Page 827 20.5.5 Creating a Socket Queue......Page 828 20.5.7 Establishing a Socket Connection......Page 829 20.5.8 Socket Shutdown......Page 830 20.6.1 Connection-Oriented Sockets on the Same Machine......Page 831 20.6.2 Connection-Oriented Sockets on Remote Machines (Internet Clients and Servers)......Page 835 20.7 The Socket.pm Module......Page 839 20.8 What You Should Know......Page 844 A.1 Perl Functions......Page 846 A.2 Special Variables......Page 876 A.3 Perl Pragmas......Page 879 A.4 Perl Modules......Page 881 A.5 Command-Line Switches......Page 887 A.6.2 The Perl Debugger......Page 889 A.6.3 Entering and Exiting the Debugger......Page 890 A.6.4 Debugger Commands......Page 891 B.1 What Is SQL?......Page 894 B.1.2 Executing SQL Statements......Page 895 B.1.3 About SQL Commands/Queries......Page 896 B.1.4 SQL and the Database......Page 899 B.1.5 SQL Database Tables......Page 900 B.2.1 The SELECT Command......Page 902 B.2.2 The INSERT Command......Page 916 B.2.3 The UPDATE Command......Page 917 B.2.4 The DELETE Statement......Page 918 B.3.1 Creating the Database......Page 919 B.3.2 SQL Data Types......Page 920 B.3.3 Creating a Table......Page 922 B.3.4 Creating a Key......Page 924 B.3.5 Relations......Page 927 B.3.6 Altering a Table......Page 930 B.4 SQL Functions......Page 932 B.4.1 Numeric Functions......Page 933 B.4.2 String Functions......Page 936 B.4.3 Date and Time Functions......Page 937 B.6 What You Should Know......Page 941 EXERCISE B......Page 943 C.2 A Little Background on DNA......Page 946 C.3 Some Perl Examples......Page 948 C.4 What Is BioPerl?......Page 950 C.5 Resources......Page 954 D.1 What Is mod_perl?......Page 956 D.2 The mod_perl Web Site......Page 958 D.3 Installing mod_perl......Page 959 D.4 Resources......Page 969 Index......Page 970 A......Page 971 B......Page 972 C......Page 973 D......Page 976 E......Page 977 F......Page 978 H......Page 983 I......Page 984 L......Page 985 M......Page 986 O......Page 989 P......Page 990 R......Page 993 S......Page 995 T......Page 999 V......Page 1000 W......Page 1001 Z......Page 1002

“I picked up a copy of JavaScript by Example over the weekend and wanted to thank you for putting out a book that makes JavaScript easy to understand. I’ve been a developer for several years now and JS has always been the “monster under the bed,” so to speak. Your book has answered a lot of questions I’ve had about the inner workings of JS but was afraid to ask. Now all I need is a book that covers Ajax and Coldfusion. Thanks again for putting together an outstanding book.”

–Chris Gomez, Web services manager, Zunch Worldwide, Inc.

“I have been reading your UNIX® Shells by Example book, and I must say, it is brilliant. Most other books do not cover all the shells, and when you have to constantly work in an organization that uses tcsh, bash, and korn, it can become very difficult. However, your book has been indispensable to me in learning the various shells and the differences between them...so I thought I’d email you, just to let you know what a great job you have done!”

–Farogh-Ahmed Usmani, B.Sc. (Honors), M.Sc., DIC, project consultant (Billing Solutions), Comverse

“I have been learning Perl for about two months now; I have a little shell scripting experience but that is it. I first started with Learning Perl by O’Reilly. Good book but lacking on the examples. I then went to Programming Perl by Larry Wall, a great book for intermediate to advanced, didn’t help me much beginning Perl. I then picked up Perl by Example, Third Edition–this book is a superb, well-written programming book. I have read many computer books and this definitely ranks in the top two, in my opinion. The examples are excellent. The author shows you the code, the output of each line, and then explains each line in every example.”

–Dan Patterson, software engineer, GuideWorks, LLC

“Ellie Quigley has written an outstanding introduction to Perl, which I used to learn the language from scratch. All one has to do is work through her examples, putz around with them, and before long, you’re relatively proficient at using the language. Even though I’ve graduated to using Programming Perl by Wall et al., I still find Quigley’s book a most useful reference.”

–Casey Machula, support systems analyst, Northern Arizona University, College of Health and Human Services

“When I look at my bookshelf, I see eleven books on Perl programming. Perl by Example, Third Edition, isn’t on the shelf; it sits on my desk, where I use it almost daily. When I bought my copy I had not programmed in several years and my programming was mostly in COBOL so I was a rank beginner at Perl. I had at that time purchased several popular books on Perl but nothing that really put it together for me. I am still no pro, but my book has many dog-eared pages and each one is a lesson I have learned and will certainly remember. “I still think it is the best Perl book on the market for anyone from a beginner to a seasoned programmer using Perl almost daily.”

–Bill Maples, network design tools and automations analyst, Fidelity National Information Services

“We are rewriting our intro to OS scripting course and selected your text for the course. It’s an exceptional book. The last time we considered it was a few years ago (second edition). The debugging and system administrator chapters at the end nailed it for us.”

–Jim Leone, Ph.D., professor and chair, Information Technology, Rochester Institute of Technology

“Quigley’s book acknowledges a major usage of PHP. To write some kind of front end user interface program that hooks to a back end MySQL database. Both are free and open source, and the combination has proved popular. Especially where the front end involves making an HTML web page with embedded PHP commands. “Not every example involves both PHP and MySQL. Though all examples have PHP. Many demonstrate how to use PHP inside an HTML file. Like writing user-defined functions, or nesting functions. Or making or using function libraries. The functions are a key idea in PHP, that take you beyond the elementary syntax. Functions also let you gainfully use code by other PHP programmers. Important if you are part of a coding group that has to divide up the programming effort in some manner.”

–Dr. Wes Boudville, CTO, Metaswarm Inc.

The World’s Easiest Perl Tutorial–Fully Updated!

Perl by Example, Fourth Edition, is the easiest, most hands-on way to learn Perl. Legendary Silicon Valley programming instructor Ellie Quigley has thoroughly updated her classic to deliver the skills and information today’s Perl users need most–including all-new coverage of MySQL database programming and a Perl QuickStart designed to get experienced users up and running fast.

Quigley illuminates every technique with focused, classroom-tested code examples, detailed line-by-line explanations, and real program output. This exceptionally clear, easy-to-understand book takes you from your first Perl script to database-driven applications. It’s the only Perl book you’ll ever need!

New in this edition:

• Perl programming QuickStart: makes first-time Perl programmers productive in just twenty pages
• All-new chapter on using the Perl DBI with the MySQL database–plus an easy SQL primer to quickly get you started programming any database
• New introductions to Perl in biology (bioinformatics) and to mod_perl, a Perl interpreter embedded in the Apache server, which allows you to create fast, dynamic content; manage the Apache server; authenticate users; and much more

Completely updated:

• Includes many new and completely rewritten code examples
• Contains fully revised CGI coverage for building dynamic Web sites with Perl
• Covers modern Perl 5.8 concepts and principles–and provides a great foundation for Perl 6

More than 30,000 sysadmins, power users, and developers have used previous editions of Perl by Example

to become expert Perl programmers. With Perl by Example, Fourth Edition, you can, too–even if you’re

completely new to Perl. After you’ve become an expert, you’ll turn to this book constantly as the best

source for reliable answers, solutions, and code.

About the CD-ROM:

The CD-ROM includes all code and files for this book’s hundreds of example scripts.

This is the eBook version of the printed book. If the print book includes a CD-ROM, this content is not included within the eBook version. “I picked up a copy of JavaScript by Example over the weekend and wanted to thank you for putting out a book that makes JavaScript easy to understand. I've been a developer for several years now and JS has always been the “monster under the bed,” so to speak. Your book has answered a lot of questions I've had about the inner workings of JS but was afraid to ask. Now all I need is a book that covers Ajax and Coldfusion. Thanks again for putting together an outstanding book.” –Chris Gomez, Web services manager, Zunch Worldwide, Inc. “I have been reading your UNIX ® Shells by Example book, and I must say, it is brilliant. Most other books do not cover all the shells, and when you have to constantly work in an organization that uses tcsh, bash, and korn, it can become very difficult. However, your book has been indispensable to me in learning the various shells and the differences between them...so I thought I'd email you, just to let you know what a great job you have done!” –Farogh-Ahmed Usmani, B.Sc. (Honors), M.Sc., DIC, project consultant (Billing Solutions), Comverse “I have been learning Perl for about two months now; I have a little shell scripting experience but that is it. I first started with Learning Perl by O'Reilly. Good book but lacking on the examples. I then went to Programming Perl by Larry Wall, a great book for intermediate to advanced, didn't help me much beginning Perl. I then picked up Perl by Example, Third Edition–this book is a superb, well-written programming book. I have read many computer books and this definitely ranks in the top two, in my opinion. The examples are excellent. The author shows you the code, the output of each line, and then explains each line in every example.” –Dan Patterson, software engineer, GuideWorks, LLC “Ellie Quigley has written an outstanding introduction to Perl, which I used to learn the language from scratch. All one has to do is work through her examples, putz around with them, and before long, you're relatively proficient at using the language. Even though I've graduated to using Programming Perl by Wall et al., I still find Quigley's book a most useful reference.” –Casey Machula, support systems analyst, Northern Arizona University, College of Health and Human Services “When I look at my bookshelf, I see eleven books on Perl programming. Perl by Example, Third Edition, isn't on the shelf; it sits on my desk, where I use it almost daily. When I bought my copy I had not programmed in several years and my programming was mostly in COBOL so I was a rank beginner at Perl. I had at that time purchased several popular books on Perl but nothing that really put it together for me. I am still no pro, but my book has many dog-eared pages and each one is a lesson I have learned and will certainly remember. “I still thin "I picked up a copy of JavaScript by Example over the weekend and wanted to thank you for putting out a book that makes JavaScript easy to understand. I've been a developer for several years now and JS has always been the "monster under the bed," so to speak. Your book has answered a lot of questions I've had about the inner workings of JS but was afraid to ask. Now all I need is a book that covers Ajax and Coldfusion. Thanks again for putting together an outstanding book."--Chris Gomez, Web services manager, Zunch Worldwide, Inc. "I have been reading your UNIX ® Shells by Example book, and I must say, it is brilliant. Most other books do not cover all the shells, and when you have to constantly work in an organization that uses tcsh, bash, and korn, it can become very difficult. However, your book has been indispensable to me in learning the various shells and the differences between them ... so I thought I'd email you, just to let you know what a great job you have done!"--Farogh-Ahmed Usmani, B. Sc. (Honors), M. Sc., DIC, project consultant (Billing Solutions), Comverse "I have been learning Perl for about two months now; I have a little shell scripting experience but that is it. I first started with Learning Perl by O'Reilly. Good book but lacking on the examples. I then went to Programming Perl by Larry Wall, a great book for intermediate to advanced, didn't help me much beginning Perl. I then picked up Perl by Example, Third Edition- this book is a superb, well-written programming book. I have read many computer books and this definitely ranks in the top two, in my opinion. The examples are excellent. The author shows you the code, the output of each line, and then explains each line in every example." - Dan Patterson, software engineer, GuideWorks, LLC "Ellie Quigley has written an outstanding introduction to Perl, which I used to learn the language from scratch. All one has to do is work through her examples, putz around with them, and before long, you're relatively proficient at using the language. Even though I've graduated to using Programming Perl by Wall et al., I still find Quigley's book a most useful reference." - Casey Machula, support systems analyst, Northern Arizona University, College of Health and Human Services "When I look at my bookshelf, I see eleven books on Perl programming. Perl by Example, Third Edition, isn't on the shelf; it sits on my desk, where I use it almost daily. When I bought my copy I had not programmed inches The practical extraction and report language -- Perl quick start -- Perl scripts -- Getting a handle on printing -- What's in a name -- Where's the operator? -- If only, unconditionally, forever -- Regular expressions-pattern matching -- Getting control-regular expression metacharacters -- Getting a handle on files -- How do subroutines function? -- Modularize it, package it, and send it to the library! -- Does this job require a reference? -- Bless those things (object-oriented Perl) -- Those magic ties and DBM stuff -- CGI and Perl: the hyper dynamic duo -- Perl meets MySQL-a perfect connection -- Interfacing with the system -- Report writing with pictures -- Send it over the net and sock it to 'em -- Appendix: A. Perl built-ins, progmas, modules, and the debugger -- B. SQL language tutorial -- C. Perl and biology -- D. Power and speed: CGI and mod_perl