Web Update
When Web server tries to open a web page, it searches the external file system first. This is usually an externally attached SD Card. If the Web server is not configured for external file system, then only the internal virtual ROM file system, which is compiled into the code, is searched.
If the requested file is found on SD Card, then the content of this file is sent to web client. If the requested file does not exist on SD Card, then the file with the same name is opened on internal ROM file system and transferred to the web client. This concept allows you to simply replace the web content from internal ROM file system with a new one, that is uploaded to external SD Card.
You should carefully update the cgi and cgx script files, as the change in the script files usually reflects in a change to the application code, which is in module HTTP_CGI.c. If you have made a mistake in the uploaded script files, the web pages might not be accessible anymore.