One way do it like this:

   use CGI;                             

   my $q = new CGI;                         
   open(OUT, '/tmp/out.html') or die "Couldn't open out file: !$"; 
   print OUT $q->header,                    
             $q->start_html('hello world'), 
             $q->h1('hello world'),         
             $q->end_html;                  
   close OUT or "Couldn't close out file: $!";
[download]

or you can redirect STDOUT in the your file:

use CGI;                             

   my $q = new CGI;     
   open(SAVE, ">&STDOUT");                    
   open(STDOUT, '/tmp/out.html') or die "Couldn't open out file: !$"; 
   print $q->header,                    
         $q->start_html('hello world'), 
         $q->h1('hello world'),         
         $q->end_html;                  
   open(STDOUT, ">&SAVE");
[download]

      
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SV* sv_bless(SV* sv, HV* stash);