Table of Contents

1. Introduction.
What is a Program? Why Perl? What about CGI? Security Issues. Perl and HTML. About This Book. What This Book is Not. What's New. The Perl and CGI VQS Guide Web Site.

2. Perl Building Blocks.
Perl Data. Operators and Functions. Quotation Marks. Quoting without Quotes. Statements, Blocks, and Scope. Declaring Private Variables. The Shebang Line. Creating a Perl CGI Script. Creating Output for a Browser. Documenting Your Script. Checking the Script's Syntax.

3. About Servers, Perl, and CGI.pm.
What is a Server? The Importance of Directories. Ask Your Web Host! Getting a Perl Interpreter. Getting CGI.pm.

4. Running Perl CGI on a Unix Server.
Which Perl are They Running? What About CGI.pm? Installing Scripts on Unix Servers. Uploading Your Script. Changing Permissions. Testing Your Unix Server.

5. Testing Scripts Locally on Windows.
Installing the Xitami or Sambar Server. Installing Personal Web Server. Installing IIS on Windows 2000. Displaying File Extensions. Testing Your Server (Part I). Installing the Perl Interpreter. Installing CGI.pm. Installing Scripts on Windows Servers. Testing Your Server (Part II).

6. Testing Scripts Locally on the Mac.
Installing Personal Web Sharing. The Root Web Directory. Carefully Sharing the Root Web Directory. Starting the Web Sharing Server. Testing the Server (Part I). Installing MacPerl. Installing CGI.pm. Installing Scripts on Mac Servers. Testing Your Server (Part II).

7. Getting Data from Visitors.
Labeling Incoming Data. Creating a Form. Creating Text Boxes. Creating Password Boxes. Creating Larger Text Areas. Creating Radio Buttons. Creating Checkboxes. Creating Menus. Creating the Submit Button. Resetting the Form. Using an Image to Submit Data. Creating a Link to a Script. Using a Link to Input Data to a Script.

8. Environment Variables.
Your Visitor's Browser and Platform. Viewing Available Environment Variables. Storing Data from Environment Variables.

9. Getting Data into the Script.
Getting Single-Valued Form Data. Getting Multiple-Valued From Data. Getting All the Form Element's Names. Getting All the Names and Values.

10. Simple Operations with Scalars.
Assigning a Value to a Scalar Variable. Multiplying, Dividing, Adding, Subtracting. Using More Than One Operator. Raising a Number to an Exponential Power. Using Mathematical Functions. Getting the Remainder of a Division. Connecting Strings Together. Repeating a String. Operating and Assigning in One Step. Incrementing (or Decrementing) a Variable.

11. Conditionals and Loops.
Comparing Numbers. Comparing Strings. Evaluating Conditions without Comparisons. Testing Two or More Comparisons at a Time. Creating a Basic Conditional Statement. Adding Options for False Conditions. Adding Multiple, Independent Conditions. Using Unless. Repeating a Block for Each Item in an Array. Loading the Default Variable. Repeating a Block While a Condition is True. Repeating a Block While a Condition is False. Executing the Block at Least Once. Repeating a Block a Given Number of Times. Nesting Conditional Statements. Skipping a Loop Iteration. Jumping Out of a Loop Altogether.

12. Working with Arrays.
Assigning a List to an Array Variable. Referring to a Particular Item in an Array. Referring to Multiple Items in an Array. Adding or Replacing an Item in an Array. Adding to the End or Beginning of an Array. Removing the Last Item from an Array. Removing the First Item from an Array. Replacing More Than One Item in an Array. Finding the Length of an Array. Modifying All the Members of an Array. Sorting Arrays. Reversing the Order of an Array's Contents.

13. Subroutines.
Creating a Simple Subroutine. Using a Simple Subroutine. Creating a Subroutine That Takes Input. Calling a Subroutine That Takes Input. Using a Subroutine's Return Value. Setting the Return Value Manually. Storing Subroutines in an External File. Calling Subroutines from an External File.

14. Working with Hashes.
Assigning a List to a Hash. Getting a Value by Using a Key. Adding or Replacing a Key-Value Pair. Getting Several Values Using Keys. Getting All of a Hash's Keys. Getting All of a Hash's Values. Getting Each Key and Value in a Hash. Getting the Pairs in a Specified Order. Removing Key-Value Pairs. Checking to See If a Key Exists.

15. Analyzing Data.
Finding Something. Finding and Replacing. Seeing and Using What was Found. Splitting a Value into Pieces. Constructing Search Patterns. Tips for Constructing Search Patterns. Matching a Single Character. Matching a String of Characters. Matching a Character from a Group. Matching a Character That's Not in the Group. Using Class Shorthands. Limiting the Locations. Choosing How Many to Match. Curbing a Quantifier's Greediness. Matching One Element or Another. More on Using What You Already Matched.

16. Remembering what Visitors Tell You.
About Hidden Fields. Adding Hidden Fields to a Form. Storing Collected Data in a Hidden Field. About Cookies. Looking at Your Browser's Cookies. Sending a Cookie. Setting a Cookie's Expiration Date. Limiting a Cookie to a Domain. Limiting a Cookie to a Part of Your Server. Limiting Cookies to Secure Connections. Reading and Using a Cookie. How (and Why) Visitors Refuse Cookies.

17. Formatting, Printing, and HTML.
Formatting Output with Perl. Creating a Format Pattern for Integers. Creating a Format Pattern for Non-Integers. Creating a Pattern for Strings. Changing the Case. Changing Characters. Finding the Length of a String. Finding Where Something is in a String. Extracting One String from Another. Cleaning up the End of a String. Formatting Output with HTML. Printing Several Lines at a Time. Simplifying Paths to Images and Links. Outputting Data in a Table.

18. Security.
Reading the Security FAQs. The Problem with Visitor Input. Protecting Calls to the Systems. Limiting Access to Files. Using CGI.pm to Limit Incoming Data. Keeping Information to Yourself. Avoiding Tainted Data. Cleaning and Using Outside Data.

19. Files and Directories.
Opening a File. Verifying File and Directory Operations. Writing to an External File. Getting Exclusive Access to a File. Reading Data from an External File. Closing a File. Renaming a File. Removing a File. Checking a File's Status. Opening a Directory. Reading the Contents of a Directory. Closing a Directory. Changing the Working Directory. Creating a Directory. Changing Permissions from within a Script. Removing a Directory. Getting Ready to E-mail Output. Sending Output via E-mail.

20. Uploading Files.
Creating a Form for Uploading Files. Getting the Name of the Uploaded File. Finding Out a File's MIME Type. Specifying Where the File Should be Saved. Reading in and Limiting the Uploaded Files.

Appendix A: Debugging.
Checking the Easy Stuff. Creating an Error Subroutine. Using Perl's Error Reporting. Viewing the System Error Log. Isolating the Problem. Following a Variable's Progress.

Appendix B: Using Other Folks' Scripts.
Using Other Folks' Scripts. Getting Other People's Scripts. Expanding Compressed Scripts. Configuring Borrowed Scripts. Customizing Borrowed Scripts.

Appendix C: Permissions on Unix.
Figuring Out the Permissions Code. Default Permissions. Who's the Owner?

Appendix D: Unix Essentials.
Telnetting to Your Unix Server. Executing Commands in Unix. Dealing with Paths in Unix. Changing the Working Directory. Finding Out Where You Are. Listing Directory Contents. Eliminating Files. Creating and Eliminating Directories. Decompressing Tar and Zipped Files. Getting Help with Unix.

Appendix E: Perl and CGI Resources.
Text Editors. Telnet Programs. Other Folks' Scripts. Learning More.

Index.

Promotional Information

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About the Author

Elizabeth Castro is the author of four best-selling editions of HTML for the World Wide Web: Visual QuickStart Guide. She also wrote the best-selling Perl and CGI for the World Wide Web: Visual QuickStart Guide, and XML for the World Wide Web: Visual QuickStart Guide.