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10.3 Maintaining State

One of the first complications for any nontrivial CGI script is how to "maintain state." Since HTTP is a stateless protocol, there's no built-in mechanism for keeping track of requests from the server end. A CGI transaction involving multiple forms, therefore, needs to find a way to remember information supplied on previous forms. One way to deal with this issue is to use cookies , which allow the CGI program to save information on the browser's end; but not all browsers support cookies, and some users are uncomfortable with the perceived privacy infringement associated with cookies.

CGI.pm simplifies maintaining state without cookies. When a CGI.pm script is called multiple times, the input fields are given default values from the previous invocation.