Server Side Includes (SSI) basically mean the Web Server itself will be reading
the HTML files as they are sent to the Web Browsers. If the Web Server sees
certain instructions "hidden" inside HTML comments the Server will act on those
instructions. Any HTML files whose name ends in ".shtml" instead of ".html"
will be processed by the Web Server looking for SSI instructions.
Only files ending in ".shtml" may have SSI inside of them. An example of
SSI is the LAST_MODIFIED date at the bottom of this page. As the web
server was sending this page to your browser, it checked to see what time
this file was last modified. It is done with the following code:
<!--#config errmsg="Bungled SSI"-->
<!--#config timefmt="%A, %B %d, %Y" -->
This page last modified: <!--#echo var="LAST_MODIFIED" -->
There are features of SSI that allow you to run arbitrary programs on
the Web Server. That was viewed as being a little bit too dangerous so
those SSI features are disabled.
This page last modified: Thursday, June 14, 2012