...
   $scriptname = ...                            # the scripts name
  (my $srv = $ENV{SERVER_NAME}) =~ s/\..+//;    # where are we now
   my $srvloc = "/srv/web/$srv/html";           # assume directory

   # prepare HTML output
   my $template = HTML::Template->new(filename => "$srvloc/cluster/$scriptname.htm");
   ...