Apache configuration has a Directory directive. It is used like a .htaccess file to control access to said directory.

An example:

Order deny,allow
Deny from all
Allow from my.domain.com

The important bit here is the Order statement. Rules will be processed from right to left (in this case all of the deny rules then all of the allow rules. The LAST rule that is matched will the the rule that is used. We are denying everyone and allowing wo we specify.

If you were to specify allow,deny you will be allowing everyone and denying who you specify.

This is quite a complicated system and some personal experimentation should help you understand.

We have written about mod_rewrite before, but did you know that you can check if a file (or directory) exists before you attempt to redirect to it? Here’s how:

RewriteCond %{DOCUMENT_ROOT}/files/%{REQUEST_URI} -f

RewriteRule ^/([^/]*)$ /files/$1 [PT]

The RewriteCond checks for the existance of a file in the specified path, this is done with the special mod_rewrite rule -f. If you want to check if a file does not exist, you could use the following:

RewriteCond %{DOCUMENT_ROOT}/%{REQUEST_URI} !-f

Also, you can check for the existance of a directory with ‘-d’

The results of the above rule will allow the user, when they visit the URL

http://example.com/foo.html

to instead be served:

http://example.com/files/foo.html

so long as /files/foo.html exists. If it doesn’t, the usual behaviour will occur (such as other rewrites/redirects running, or causing a 404 error to be displayed).

Sometimes you want to redirect the user to a new page based on a specific query string value. Heres  how to do that:


RewriteCond %{QUERY_STRING} foo=bar&bim=bam
RewriteRule ^horrible.php$ /farbetter.html? [R=302]


This redirects all traffic going to “horrible.php?foo=bar&bim=bam” to goto “farbetter.html”. Note that for all other querystring vars horrible.php is still available.

Multiple domains pointing to a single site? Want to divert the traffic based on domain name? Then this is the simple two liner to do it without faffing with virtualhosts.


RewriteCond %{HTTP_HOST} ^(www\.)?mywebsite.com$
RewriteRule    ^/$  /mywebsite.html [L]

RewriteCond %{HTTP_HOST} ^(www\.)?myotherwebsite.com$
RewriteRule ^/$ /myotherwebsite.html [L]