#!/usr/bin/perl -w 
use CGI qw/ fatalsToBrowser/; # don't do this in production
use strict;
require "myfile.pl";

&foo(); # &foo is defined in myfile.pl

##</code><code>##

.
.
. #much handwaving

exec($0);
.
.
.

##</code><code>##

:
:
# NOTE: $q was defined elsewhere as my $q=new CGI;
print $q->redirect("http://my.site.tld/cgi-bin/foo.cgi?...")
:
:
: