DOCUMENT_ROOT

The root directory of your server

HTTP_COOKIE

The visitor's cookie, if one is set

HTTP_HOST

The hostname of the page being attempted

HTTP_REFERER

The URL of the page that called your program

HTTPUSER_AGENT

The browser type of the visitor

HTTPS

"on" if the program is being called through a secure server

PATH

The system path your server is running under

QUERY_STRING

The query string (see GET, below)

REMOTE_ADDR

The IP address of the visitor

REMOTE_HOST

The hostname of the visitor (if your server has reverse-name-lookups on; otherwise this is the IP address again)

REMOTE_PORT

The port the visitor is connected to on the web server

REMOTE_USER

The visitor's username (for .htaccess-protected pages)

REQUEST_METHOD

GET or POST

REQUEST_URI

The interpreted pathname of the requested document or CGI (relative to the document root)

SCRIPT_FILENAME

The full pathname of the current CGI

SCRIPT_NAME

The interpreted pathname of the current CGI (relative to the document root)

SERVER_ADMIN

The email address for your server's webmaster

SERVER_NAME

Your server's fully qualified domain name (e.g. www.cgi101.com)

SERVER_PORT

The port number your server is listening on

SERVER_SOFTWARE

The server software you're using (e.g. Apache 1.3)