The CGI Book: The Complete World Wide Web Programming Reference

Focusing on CGI programs written in sh, C, and Perl, Weinman begins by dissecting several "Hello, World" CGI programs and explaining how they work. Then, he explains the CGI methods and environment variables. (The environment variables are helpfully grouped by function, such as those that tell about the server and those that describe the client.) The book proceeds to discuss form handling in depth and gives special attention to authentication routines.

The CGI Book distinguishes itself in its discussion of advanced CGI topics, covering server-side includes (SSI), push systems, and cookies--both temporary and persistent. The book includes several shopping-cart examples in both Perl and C. (These examples, along with those that appear throughout the book, appear on the accompanying CD-ROM.)

You may want better coverage of image maps and databases but, overall, The CGI Book is an excellent choice for the intermediate programmer who wants to acquire a deep understanding of how CGI works while using it to solve real-world problems.