CGI Environment Variables
All the CGI programs have access to the following environment variables. These variables play an important role while writing any CGI program.
| Sr.No. | Variable Name | Description |
| 1 | CONTENT_TYPE | The data type of the content. Used when the client is sending attached content to the server. For example, file upload. |
| 2 | CONTENT_LENGTH | The length of the query information. It is available only for POST requests. |
| 3 | HTTP_COOKIE | Returns the set cookies in the form of key & value pair. |
| 4 | HTTP_USER_AGENT | The User-Agent request-header field contains information about the user agent originating the request. It is name of the web browser. |
| 5 | PATH_INFO | The path for the CGI script. |
| 6 | QUERY_STRING | The URL-encoded information that is sent with GET method request. |
| 7 | REMOTE_ADDR | The IP address of the remote host making the request. This is useful logging or for authentication. |
| 8 | REMOTE_HOST | The fully qualified name of the host making the request. If this information is not available, then REMOTE_ADDR can be used to get IR address. |
| 9 | REQUEST_METHOD | The method used to make the request. The most common methods are GET and POST. |
| 10 | SCRIPT_FILENAME | The full path to the CGI script. |
| 11 | SCRIPT_NAME | The name of the CGI script. |
| 12 | SERVER_NAME | The server's hostname or IP Address |
| 13 | SERVER_SOFTWARE | The name and version of the software the server is running. |