Translating htaccess rewrite rules to Apache2 virtualhost rules

I'm trying to set a wildcard subdomain RewriteRule by combining some .htaccess rules I'd successfully implemented before, under the belief that I can use the same rules for my Apache vhosts file.

In essence, example.com and www.example.com go to the root path and look for index.php. All other (dynamic) subdomain requests at root level such as abc.example.com get rewritten (invisible to the browser) to example.com/process.php?p=abc.

Secondly, any requests for files from the subdomain outside of a base/root level need to be rewritten to be obtained from the root path of the standard domain without the subdomain. So abc.example.com/css/style.css needs to come from example.com/css/style.css

This is my attempt at doing so. I get an Apache error:

You don't have permission to access /index.php on this server.

for any subdomain attempt, other than www, which works as expected, as well as the standard example.com, which still works fine.

<VirtualHost *:80> ServerAdmin [email protected] ServerName example.com ServerAlias www.example.com DocumentRoot /var/www/example.com/public_html ErrorLog ${APACHE_LOG_DIR}/error.log CustomLog ${APACHE_LOG_DIR}/access.log combined </VirtualHost> <VirtualHost *:80> ServerAdmin [email protected] ServerName other.example.com ServerAlias *.example.com DocumentRoot /var/www/example.com/public_html/ <Directory /var/www/example.com/public_html/> Options FollowSymLinks AllowOverride all Require all granted RewriteCond %{HTTP_HOST} !^www\.example\.com$ [NC] RewriteCond %{HTTP_HOST} ^(www\.)?([^\.]+)\.example\.com$ [NC] RewriteRule ^$ /process.php?p=%2 [QSA,NC] RewriteCond %{REQUEST_FILENAME} !^$ [NC] RewriteRule ^(.*) http://www.example.com/$1 [P] </Directory> </VirtualHost> 

I'd based this off successfully redirecting a different domain's root directory to example.com using this .htaccess file, which incorporates process.php and sends all other requests to the root of example.com.

Options +FollowSymLinks RewriteEngine On RewriteBase / # Check the request isn't an existing file RewriteCond %{REQUEST_FILENAME} !-f RewriteRule ^$ http://www.example.com/process.php [P] RewriteCond %{REQUEST_FILENAME} !^$ [NC] RewriteRule ^(.*) http://www.example.com/$1 [P] 

And also off this .htaccess test I ran to redirect a subdomain as a variable to process.php succesfully, though it didn't catch other file requests, such as the css example above:

Options +FollowSymLinks RewriteEngine On RewriteBase / RewriteCond %{HTTP_HOST} !^www\.example\.com$ [NC] RewriteCond %{HTTP_HOST} ^(www\.)?([^\.]+)\.example\.com$ [NC] RewriteRule ^$ /process.php?p=%2 [QSA,NC] 

Update 1

I've had (seemingly) some success with using the following in place of my second virtualhost entry. The process.php page is being output if I use a subdomain. While the pattern matching seems to work in that regard, my actual process.php receives an empty variable, rather than the expected subdomain as a string (for: process.php?p=%2):

<VirtualHost *:80> ServerAdmin [email protected] ServerName other.example.com ServerAlias *.example.com DocumentRoot /var/www/example.com/public_html <Directory /var/www/example.com/public_html> Options FollowSymLinks AllowOverride all Require all granted RewriteEngine on RewriteBase / RewriteCond %{HTTP_HOST} !^www\.example\.com$ [NC] RewriteCond %{HTTP_HOST} ^(www\.)?([^\.]+)\.example\.com$ [NC] RewriteCond %{REQUEST_URI} ^/$ RewriteRule ^$ /process.php?p=%2 [NC,QSA] </Directory> </VirtualHost> 

Update 2

I've solved this in a roundabout way but I'm not sure if it's the most elegant way of doing so.

Using the above update 1 code, I saw that any query string was still being appended but %2 was not being received by GET in my process.php page. I may have assumed wrongly that although the url doesn't display the p=abc variable in the url to the browser, as per my code instructions, that the internal url still passed them on. Nonetheless, I realised that process.php could still determine the subdomain as a string using $_SERVER['HTTP_X_FORWARDED_HOST'] in PHP and use it as a variable on the page in a similar manner to my initial idea.