User Guide

30 Chapter 1: Reserved Words and Variables

Testing for CGI variables

Because some browsers do not support some CGI variables, ColdFusion always returns True

when it tests for the existence of a CGI variable, regardless of whether the browser supports the

variable. To determine if the CGI variable is available, test for an empty string, as shown in the

following example:

CGI variable exists

CGI variable does not exist

</cfif>

CGI server variables

The following table describes common CGI environment variables that the server creates (some

of these are not available with some servers):

CGI server variable Description

SERVER_SOFTWARE Name and version of the information server software answering the

request (and running the gateway). Format: name/version.

SERVER_NAME Server's hostname, DNS alias, or IP address as it appears in self-

referencing URLs.

GATEWAY_INTERFACE CGI specification revision with which this server complies. Format: CGI/

revision.

SERVER_PROTOCOL Name and revision of the information protocol this request came in with.

Format: protocol/revision.

SERVER_PORT Port number to which the request was sent.

REQUEST_METHOD Method with which the request was made. For HTTP, this is Get, Head,

Post, and so on.

PATH_INFO Extra path information, as given by the client. Scripts can be accessed

by their virtual pathname, followed by extra information at the end of this

path. The extra information is sent as PATH_INFO.

PATH_TRANSLATED Translated version of PATH_INFO after any virtual-to-physical mapping.

SCRIPT_NAME Virtual path to the script that is executing; used for self-referencing

URLs.

QUERY_STRING Query information that follows the ? in the URL that referenced this

script.

REMOTE_HOST Hostname making the request. If the server does not have this

information, it sets REMOTE_ADDR and does not set

REMOTE_HOST.

REMOTE_ADDR IP address of the remote host making the request.

AUTH_TYPE If the server supports user authentication, and the script is protected, the

protocol-specific authentication method used to validate the user.

REMOTE_USER

AUTH_USER

If the server supports user authentication, and the script is protected, the

username the user has authenticated as. (Also available as

AUTH_USER.)