Perl

With a worldwide community of users and more than a million dedicated programmers, Perl has proven to be the most effective language for the latest trends in computing and business.Every programmer must keep up with the latest tools and techniques. This updated version of Advanced Perl Programming from O'Reilly gives you the essential knowledge of the modern Perl programmer. Whatever your current level of Perl expertise, this book will help you push your skills to the next level and become a more accomplished programmer.

Perl is a general-purpose programming language originally developed for text manipulation and now used for a wide range of tasks including system administration, web development, network programming, GUI development, and more.

The language is intended to be practical (easy to use, efficient, complete) rather than beautiful (tiny, elegant, minimal). Its major features are that it's easy to use, supports both procedural and object-oriented (OO) programming, has powerful built-in support for text processing, and has a large collection of third-party modules.

The Common Gateway Interface (CGI) is a standard protocol for interfacing external application software with an information server, commonly a web server. This allows the server to pass requests from a client web browser to the external application. The web server can then return the output from the application to the web browser.

CGI arose out of discussions on the www-talk mailing list between Rob McCool, John Franks, Ari Luotonen, George Phillips and Tony Sanders in 1993. Rob McCool, working at NCSA, drafted the initial specification and provided a reference implementation in the NCSA HTTPd web server using environment variables to store parameters passed from the web server execution environment before spawning the CGI program as a separate process.

The way CGI works from the Web server's point of view is that certain locations (e.g. http://www.example.com/wiki.cgi) are defined to be served by a CGI program. Whenever a request to a matching URL is received, the corresponding program is called, with any data that the client sent as input. Output from the program is collected by the Web server, augmented with appropriate headers, and sent back to the client.