use strict;
use warnings;
use CGI;
my $q = new CGI;
my $user = $q->param('user');
my $age = $q->param('age');
$user = 'Anonymous' if !defined $user;
$age = '?' if !defined $age;
print $q->header("text/plain"), "Hello $user.\n", "You are $age years old.\n";
---
$ perl foo.cgi user=hoge age=123
Content-Type: text/plain; charset=ISO-8859-1
Hello hoge.
You are 123 years old.