$servers_file = $ENV{'HTTP_GETTER_SERVERS_FILE'} || $servers_file;
$uris_dbm = $ENV{'HTTP_GETTER_URIS_DBM'} || $uris_dbm;
$dtdbaseurl = $ENV{'HTTP_GETTER_DTD_BASE_URL'} || $dtdbaseurl;
$servers_file = $ENV{'HTTP_GETTER_SERVERS_FILE'} || $servers_file;
$uris_dbm = $ENV{'HTTP_GETTER_URIS_DBM'} || $uris_dbm;
$dtdbaseurl = $ENV{'HTTP_GETTER_DTD_BASE_URL'} || $dtdbaseurl;