Since you're using a file:// URL to display your log.html, support for auto-refreshing that seems to vary between browsers. For Chrome, the Tincr extension at http://tin.cr/ sounds like it might do the trick. Otherwise, Google browser refresh local file or similar.

Of course, you could just set up a regular refresh of the page, but then it'll refresh itself constantly, even when the file doesn't change.

If you want a more general solution, perhaps you should serve up your log.html through an HTTP server, where you can control cache timeout values.

like you, i initially thought this was a matter due to caching. i then changed my script to serve a file that has NEVER PREVIOUSLY been opened in the browser (to see if in fact, the client browser would request in response to the redirect HTTP headers). unfortunately, the file referenced in the HTTP redirect was NOT opened in the browser - so this tells me the problem has nothing to do with caching.

ive distilled the program down to its 'bare-bones' version to show the relevant code. this is not my actual program, but only serves to demonstrate the problem.

use HTTP::Daemon;
use LWP::UserAgent;

my $ua = LWP::UserAgent->new();
my $d  = HTTP::Daemon->new( 
         LocalHost => "localhost",  # remove this to listen from other
+ machines 
                                    # (i.e. open-relay... be careful o
+f spammers!)
     LocalPort => 8888          #always best to run 'netstat -ano | fi
+nd "8888"' prior to running this command (to find an unused port)
) || die;                           #after this program is launched ru
+n again 'netstat -ano | find "8888"' to confirm this port is now bein
+g bound to this program
                                    #then to actually use this with a 
+browser must go to browsers proxy setting (a global windows setting):
+ set server=127.0.0.1 port=8888

#main 'accept-getrequest-process' loop is the next two lines
while (my $c = $d->accept) {
   while (my $request = $c->get_request) {

      #we wish to send the web client browser a redirect to a local fi
+le on his same machine
      #as a test of the nifty 'send_redirect' function
      #since this particular file has never before been opened in the 
+web browser
      #if it does NOT open/display in the client web browser
      #the fault for this can NOT be attributed to caching issues
      #unfortunately, when this proxy program is ran, and the computer
+ environment told to use this proxy
      #this page never displays in the client web browser window (i am
+ unsure as to why it does not display.
      #ive also tried various "300" codes, 301, 302,303, 307 with no c
+hange in the result.)

      #because 'Wireshark' cant capture traffic thats on the localhost
+ (eg: not being sent out of the network card)
      #i have no way to 'view' the actual data being sent between the 
+client program and the proxy program (on Windows)

      $c->send_redirect("file:///C:/http_proxy_server/FileThatsNeverBe
+foreBeenOpenedInTheBrowser_eg-NotCached.html", 303);

   }
   $c->close;
   undef($c);
}
[download]

note because the client (browser app) and server (perl proxy server program) are both running on the same machine - this is particularly hard to troubleshoot as 'wireshark' does not capture any TCP packets that are not actually sent out of the network card. does anyone know how to monitor TCP/IP traffic sent/received to the 'localhost' only?

According to the Browser Security Handbook, it's not possible for websites to redirect to file: URLs. The rationale is explained a bit in the section "URL scheme access rules" just before the linked section.

Since you've already got a working HTTP server, why not serve the file over that, via a special URL?

Just a thought; have you made sure the log file has been properly written and closed before you send the "redirect" response? If not, you may be redirecting the browser to a file that isn't ready yet, and you will get the old log file (or no logfile) ...unless the browser happens to be just slow enough for the intended mechanism to work anyway.