CGI and Perl in Easy Steps [Paperback]

Starting with "Perl Tools & Environment", this chapter introduces the world of CGI & Perl. It shows how to download and install the free Perl interpreter that is needed to run Perl scripts. The benefits and features of a purpose-built Perl editor are demonstrated, and there is a guide to download and install the free Xitami web server to create a local CGI Intranet environment.

The author then moves on to "Getting Started", in a chapter that illustrates a first Perl script and introduces the three variable types that are used to store information. Syntax rules of the Perl language are discussed and data joining (concatenation) is demonstrated.

Chapter Three demonstrates the many ways that Perl operators can manipulate script values and provides examples of each: Arithmetic, Assignment and Logical Operators; Numeric and String Comparisons; Conditional and Range Operators; Math Functions; Escape Sequences. Next, the author shows how to write statements in Perl script. Conditional branching is demonstrated and each type of loop statement is explained and illustrated.

"Using Arrays" is a chapter devoted to the array variable, which can contain multiple pieces of data. Areas covered are: Create An Array; Referencing Elements; Convert Scalar to Array; Fill Elements Loop; Address All Elements; Subarrays; Add/Remove First and Last Element; Combining Arrays; Replacing Elements; Sort Alphabetically and Numerically; Slice and Reverse.

"Using Hashes" covers the hash variable type that is so important to handling HTML form data in CGI scripts. A hash variable is a special type of array that arranges its data in pairs that form an "associative array". This chapter provides examples and demonstrates how to usefully handle the hash data in Perl scripts. The author then moves on to "Subroutines" and describes by example, how subroutines can be useful to define pieces of code that can be used repeatedly in a Perl script.

Chapter Eight illustrates how "Perl Functions" are useful in CGI scripting. Time and Currency formatting are demonstrated along with random number generation. Other useful functions covered are: Random Generator; Random Floats; Data Formatting; Currency Format; Handling Time; Chop String; Chomp New Lines; Eval; Warn and Die; Pack.

Next, performing "Pattern Matching" is covered, by demonstrating how located matches can be manipulated in a variety of useful ways. This chapter also introduces 'Regular Expressions' to search through a string for a specified substring. Further areas covered are: Match String; View Match; Substitute String; Split Pattern; Translate; Character Classes; Inclusive and Exclusive Groups; Limited and Optional Matching; Minimum, Alternative and Multiple Matches.

Chapter Ten looks at "CGI from Web Pages" and demonstrates how web pages can interact with Perl script using CGI. Different methods of sending data from the browser to the server are demonstrated. The form parser is detailed in full, and examples are given in sending data back to the browser.

The author then moves on to "Working with Files" and illustrates how Perl CGI scripts can read and write text files on the server. There are demonstrations of how these features can be used to create a simple hit counter and guest book. Next, a chapter on " Handling Directories" illustrates how to work with files and directory structures. Creation and deletion of directories is demonstrated. File permissions are explained with examples of how they can be changed by Perl scripts.

"Data Persistence" illustrates how user data can be retained as the user browses across different web pages. These are demonstrations on how to store data in hidden firms, in server files and in browser cookies. Also examples are provided that demonstrate how access to cookie information is restricted.

Moving on to "Form Inputs", this chapter demonstrates how Perl CGI scripts can use different types of HTML form input from check boxes, radio buttons, and options menus. Also examples show how Perl can navigate between web pages and send email. Lastly a survey application illustrates some of these features in use.

The final chapter "Upload and Run Scripts", demonstrates how to upload Perl CGI scripts to a web server so that the scripts will perform correctly. Examples illustrate how scripts can be restricted to run only from origins on the same server. Using third-party scripts and libraries is explained with addresses where CGI resources can be obtained for free.

PUB COMMENTS: Mike McGrath is an expert on web development and has written other best selling in easy steps titles including 'WAP in easy steps' and 'JavaScript in easy steps'.