Server Side Includes - XBitHack

[Robert Dinse <nanook@eskimo.com>]

     I have enabled the XBitHack feature of Apache in "full" mode.

     This has some important ramifactions even for files which do not use
server side includes, particularly CGI scripts.

     This feature does two things:

	1) Now instead of having to name files with an extension of ".shtml"
	   in order to have the server parse them for SSI directives, you can
	   set the user execute bit on a file with .html or .htm extensions:

		chmod u+x file.html

	2) The group execute bit now has special meaning, if set, proxy servers
	   will be allowed to cache the result.  This has very important
	   ramifications for CGI's which produce dynamic content or which must
	   not have their output cached.  CGI's such as counters or banner
	   advertisements or anything which produces dynamic content must NOT
	   have their group execute bit set.

     The main reason I enabled this feature is that I really needed to use
server side includes to make management of our web site workable.  Right now I
have to exit approximately 50 files to change a menu bar option, six files to
add a new state to the coverage area, several hundred files to make a change to
font or colors, etc.  If I had to re-name everything .shtml not only would it
be a lot of editing but it would break existing search engine pointers. 

     But a secondary plus is that those of you working on DOS systems limited
to a three character extension can now use server side includes with the .htm
extension. 

     I enabled the full feature which includes support for allowing or
disallowing cacheing based on the group execution bit because it is convenient
to be able to specify this on a per file basis. 

     However, because CGI's will have the user execute bit set by default (else
it can't run), it's important to make sure the group execute bit is not also
set or your counter results, banner ads, etc, will be cached in proxy servers,
you'll see fewer hits on the counter, the customer will see the same counter
value, banner ad, etc.