CGI Environment Variables
Most of the information needed by CGI programs is made available
via Unix environment variables. Programs can access this information
as they would any environment variable (via the %ENV
hash in Perl).
The table below lists environment variables commonly available
through CGI. However, since servers occasionally vary on
the names of environment variables they assign, check with your
own server documentation for more information.
Environment Variable | Content Returned |
---|---|
AUTH_TYPE |
The authentication method used to validate a user. See REMOTE_IDENT and REMOTE_USER. |
CONTENT_LENGTH |
The length of the query data (in bytes or the number of characters) passed to the CGI program through standard input. |
CONTENT_TYPE |
The media type of the query data, such as |
DOCUMENT_ROOT |
The directory from which web documents are served. |
GATEWAY_INTERFACE |
The revision of the Common Gateway Interface that the server uses. |
HTTP_ACCEPT |
A list of the media types that the client can accept. |
HTTP_COOKIE |
A list of cookies defined for that URL. |
HTTP_FROM |
The email address of the user making the query (many browsers do not support this variable). |
HTTP_REFERER |
The URL of the document the client read before accessing the CGI program. |
HTTP_USER_AGENT |
The browser the client is using to issue the request. |
PATH_INFO |
Extra path information passed to a CGI program. |
PATH_TRANSLATED |
The translated version of the path given by the variable PATH_INFO. |
QUERY_STRING |
The query ... |
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