“Hello, world!” as a CGI Script
Before ending this brief introduction to Perl, I want to show you one more thing: the “Hello, world!” script rewritten to run as a CGI script.
I’ve assumed in this book that you already have a certain
amount of web authoring experience, so you may have encountered CGI
scripts before, and may even have run a few yourself. In case
they’re completely new to you, though, here’s the
lowdown: In simplest terms, a CGI script is a
separate program that a web server runs in order to produce a
customized page to show to a web user. CGI stands for
, which is
just a description of a set of relatively simple rules for how the
communication between the web server and the separate program will be
conducted. CGI scripts can be written in any language that can
produce the appropriate sort of output, but Perl is by far the most
popular choice because of how easy it is to create CGI scripts in
CGI scripts are something of a gateway drug for Perl use. Many accidental programmers first come to Perl not because they’ve decided to learn Perl programming per se, but because they want to create a CGI script (probably to process the output of a web form), and someone has told them that Perl is the way to go. That’s okay; Perl doesn’t mind. It happily does the task at hand, biding its time until the user is ready for more.
hello.plx so that it will run
as a CGI script. Every CGI script needs to output a
CGI header ...