| SERVER SIDE INCLUDES
( SSI )
Server Side Includes
(SSI)
SSI is an old but still effective way to simplify
certain web page tasks. Essentially, with SSIs you can "include"
pages or scripts in the text of a web page without having
to write it out every time. A perfect example is a page footer,
like the one at the bottom of this page - that can be referenced
in a single line, and then when we want to make changes we
can change just the single footer file rather than the html
on every page that uses the footer. SSI can include information
like current date, the file's last modification date, and
the size or last modification of other files.
Every hosting account supports Server Side Includes
automatically!
IMPORTANT: in order for SSIs to work, your
file must be named with the ".shtml" extension.
SSI can be used to output the last modification
date of the file the user requested. This is done by using
the "echo" element and the LAST_MODIFIED variable. The command
would be:
<!--#echo var="LAST_MODIFIED"
-->
Other variables that can be output in this
fashion include DATE_LOCAL (date in the local time zone,
EST), DATE_GMT (date in Greenwich Mean Time), DOCUMENT_NAME
(the filename of the document), and DOCUMENT_URI (the URL
path of the document).
Another common use of SSI is to include the
output of a CGI script within your page. The SSI command
to do so is:
<!--#exec cgi="/cgi-bin/included_script.cgi"
-->
The most common use for SSI is probably including
a file within your page. This could be used to have a common
footer on every page, for instance, while still being able to
change it by altering a single file. Including a file via SSI
is done with:
<!--#include virtual="/filename.html" -->
The value of the "virtual" attribute is derived
from the URL needed to view the file under your domain name,
minus the domain name and "http://". For instance, if the
file to be included is located at http://www.example.com/files/includes/first.txt,
your call to include it in other files under that domain would
be:
<!--#include virtual="/files/includes/first.txt"
-->
In some cases, you may want every .html file
to be parsed for SSI. This can be done with the following
command in your .htaccess file:
AddType text/x-server-parsed-html .html
Note: Please do not do this unless you genuinely
intend to use SSI in all of your files. The unnecessary overhead
of parsing the files that do not actually use SSI will slow
the server down and make your site less responsive (each file
will take longer to download as the server must process every
file).
Also, don't do this for .shtml files; it will
make them stop working!
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