#**** SCRIPT STARTS ****

# get the URL for the Web page that called this script
$calling_page = $ENV{'HTTP_REFERER'};
# when the browser is Netscape, the referrer can contain the # and anchor name: REMOVE IT! (eg. http://hostname/file.htm#anchorname)

if($calling_page =~ /(.*)\#.*/) {
    # only take the first part up to the #
    $calling_page = $1;}

# ignore any file that is not _e.htm or _f.htm and do nothing!

# is this an _e.htm file?

if($calling_page =~ /_e\.htm/) {
    # replace the suffix
    $calling_page =~ s/_e\.htm/_f\.htm/;
    print "Location: $calling_page\n\n";

# then is this an _f.htm file?

} elsif($calling_page =~ /_f\.htm/) {
    # replace the suffix
    $calling_page =~ s/_f\.htm/_e\.htm/;
    print "Location: $calling_page\n\n";}

#**** SCRIPT ENDS ****