Server Environment Variables DOCUMENT_ROOT     The directory from which the web documents are served GATEWAY_INTERFACE    The revision of the Common Gateway Interface that the server uses HTTP_ACCEPT    A list of MIME types that the client can accept HTTP_ACCEPT_ENCODING    A list of ENCODING types that the client can accept ( gzip, deflate ) HTTP_ACCEPT_LANGUAGE:    A list of LANGUAGE types that the client can accept ( en-us ) HTTP_HOST    The hostname of the server HTTP_USER_AGENT    The browser the client is using to issue the request HTTP_REFERER    The URL of the document that the client was at before accessing current file or program PATH_INFO    Directory path information of the server QUERY_STRING    The query information passed to the program (appended to the URL with a "?") REMOTE_ADDR    The remote IP address of the user making the request REMOTE_PORT    The port number of the remote host making the request REQUEST_METHOD    The method with which the request was issued ( GET or POST ) REQUEST_URI, SCRIPT_NAME, and SCRIPT_URL    The virtual URL path of the script being executed SCRIPT_URI    The full URL path of the script being executed (including http://) SCRIPT_FILENAME    The directory path information of the script being executed SERVER_ADDR    The server's IP address SERVER_ADMIN    The server's admininstrator email address SERVER_NAME    The server's hostname or IP address SERVER_PORT    The port number of the host on which the server is running (usually 80) SERVER_SOFTWARE    The name and version of the server software that is answering the client request SERVER_PROTOCOL    The name and revision of the information protocol the request came with UNIQUE_ID    A unique server session id assigned to each client request