CGI Environment Variables

In order to pass data about the information request from the server to the script, the server uses command line arguments as well as environment variables. These environment variables are set when the server executes the gateway program.

Specification

The following environment variables are not request-specific and are set for all requests:

• SERVER_SOFTWARE

  The name and version of the information server software answering the request (and running the gateway). Format: name/version

• SERVER_NAME

  The server's hostname, DNS alias, or IP address as it would appear in self-referencing URLs.

• GATEWAY_INTERFACE

  The revision of the CGI specification to which this server complies. Format: CGI/revision

• SERVER_PROTOCOL

  The name and revision of the information protcol this request came in with. Format: protocol/revision

• SERVER_PORT

  The port number to which the request was sent.

• REQUEST_METHOD

  The method with which the request was made. For HTTP, this is "GET", "HEAD", "POST", etc.

• HTTP_ACCEPT

  The MIME types which the client will accept, as given by HTTP headers. Other protocols may need to get this information from elsewhere. Each item in this list should be separated by commas as per the HTTP spec.

  Format: type/subtype, type/subtype

• PATH_INFO

  The extra path information, as given by the client. In other words, 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. This information should be decoded by the server if it comes from a URL before it is passed to the CGI script.

• PATH_TRANSLATED

  The server provides a translated version of PATH_INFO, which takes the path and does any virtual-to-physical mapping to it.

• SCRIPT_NAME

  A virtual path to the script being executed, used for self-referencing URLs.

• QUERY_STRING

  The information which follows the ? in the URL which referenced this script. This is the query information. It should not be decoded in any fashion. This variable should always be set when there is query information, regardless of command line decoding.

• REMOTE_HOST

  The hostname making the request. If the server does not have this information, it should set REMOTE_ADDR and leave this unset.

• REMOTE_ADDR

  The IP address of the remote host making the request.

• AUTH_TYPE

  If the server supports user authentication, and the script is protects, this is the protocol-specific authentication method used to validate the user.

• REMOTE_USER

  If the server supports user authentication, and the script is protected, this is the username they have authenticated as.

• CONTENT_TYPE

  For queries which have attached information, such as HTTP POST and PUT, this is the content type of the data.

• CONTENT_LENGTH

  The length of the said content as given by the client.

Examples

Return to the interface specification

Rob McCool robm@ncsa.uiuc.edu