Enabling SSI Via htaccess
Many people want to use SSI, but don't seem to have the ability to do so with their current web host. You can change that with htaccess. A note of caution first...definitely ask permission from your host before you do this, it can be considered 'hacking' or violation of your host's TOS, so be safe rather than sorry:
AddType text/html .shtml AddHandler server-parsed .shtml Options Indexes FollowSymLinks Includes
The first line tells the server that pages with a .shtml extension (for Server parsed HTML) are valid. The second line adds a handler, the actual SSI bit, in all files named .shtml. This tells the server that any file named .shtml should be parsed for server side commands. The last line is just techno-junk that you should throw in there.
And that's it, you should have SSI enabled. But wait...don't feel like renaming all of your pages to .shtml in order to take advantage of this neat little toy? Me either! Just add this line to the fragment above, between the first and second lines:
AddHandler server-parsed .html
A note of caution on that one too, however. This will force the server to parse every page named .html for SSI commands, even if they have no SSI commands within them. If you are using SSI sparingly on your site, this is going to give you more server drain than you can justify. SSI does slow down a server because it does extra stuff before serving up a page, although in human terms of speed, it is virtually transparent. Some people also prefer to allow SSI in html pages so as to avoid letting anyone who looks at the page extension to know that they are using SSI in order to prevent the server being compromised through SSI hacks, which is possible. Either way, you now have the knowledge to use it either way.
If, however, you are going to keep SSI pages with the extension of .shtml, and you want to use SSI on your Index pages, you need to add the following line to your htaccess:
DirectoryIndex index.shtml index.html
This allows a page named index.shtml to be your default page, and if that is not found, index.html is loaded. More on DirectoryIndex later.