Writing and Running CGI Scripts

CGI scripts can exist in many forms -- depending upon what the server supports.

CGI scripts can be compiled programs or batch files or any executable entity. For simplicity we will use the term script for all CGI entities.

Typically CGI scripts are written in:

• Perl scripts
• C/C++ programs
• Unix Scripts

We will concentrate on Perl in this course (see below for why this is a good idea).

CGI scripts therefore have to be written (and maybe compiled) and checked for errors before they are run on the server.

CGI can be called and run in a variety of ways on the server.

The 2 most common ways of running a CGI script are:

• From an HTML Form -- the ACTION attribute of the form specifies the CGI script to be run.
• Direct URL reference -- A CGI script can be run directly by giving the URL explicitly in HTML.
  • Arguments (values) may be required by the script this will have to passed in.
  • We will see how to do this shortly.

One other way CGI scripts are called is in Server-side include HTML commands. This is something we will leave until later.