htaccess reverse directory

Question

It is possible to let htaccess look for a specific file related to the url and go back one step if not found?

Example:

/example/here/where/from

Answer 1

This is very tricky but here is a code that recursively traverse to parent dir of the given REQUEST_URI and it supports infinite depth.

Enable mod_rewrite and .htaccess through httpd.conf and then put this code in your .htaccess under DOCUMENT_ROOT directory:

# Turn mod_rewrite on
RewriteEngine On
RewriteBase /

# If the request is for a valid file
RewriteCond %{REQUEST_FILENAME} -f [OR]
# If the request is for a valid link
RewriteCond %{REQUEST_FILENAME} -l
# don't do anything
RewriteRule ^ - [L]

# if current ${REQUEST_URI}.php is not a file then
# forward to the parent directory of current REQUEST_URI
RewriteCond %{DOCUMENT_ROOT}/$1/$2.php !-f
RewriteRule ^(.*?)/([^/]+)/?$ $1/ [L]

# if current ${REQUEST_URI}.php is a valid file then 
# load it be removing optional trailing slash
RewriteCond %{DOCUMENT_ROOT}/$1.php -f
RewriteRule ^(.*?)/?$ $1.php [L]

Explanation:

Let's say original URI is: /index/foo/bar/baz. Also let's say that %{DOCUMENT_ROOT}/index.php exists but no other php files exist under DOCUMENT_ROOT.

RewriteRule #1 has a regex that is breaking current REQUEST_URI into 2 parts:

1. All but lowest subdir into $1 which will be index/foo/bar here
2. Lowest subdir into $2 which will be baz here

RewriteCond checks whether %{DOCUMENT_ROOT}/$1/$2.php (which translates to whether %{DOCUMENT_ROOT}/index/foo/bar/baz.php) is NOT a valid file.

If condition succeeds then it is internally redirected to $1/ which is index/foo/bar/ here.

RewriteRule #1's logic is repeated again to make REQUEST_URI as (after each recursion):

1. index/foo/bar/
2. index/foo/
3. index/

At this point RewriteCond fails for rule # 1 because ${DOCUMENT_ROOT}/index.php exists there.

My RewriteRule #2 says forward to $1.php if %{DOCUMENT_ROOT}/$1.php is a valid file. Note that RewriteRule #2 has regex that matches everything but last slash and puts it into $1. This means checking whether %{DOCUMENT_ROOT}/index.php is a valid file (and it indeed is).

At this point mod_rewrite processing is complete as no further rule can be fired since both RewriteCond fails after that, therefore %{DOCUMENT_ROOT}/index.php gets duly served by your Apache web server.