New to .htaccess and RewriteRule

Question

I'm making a site where users can create subdomains with files, folders etc. these sites go into a folder called websites so it will be

site.com/websites/subdomain.site.com

I only need to get {REQUEST_URI} at the end of the RewriteRule so that a user can go to example, subdomain.site.com/images/etc/img.jpg and still their subdomain will be shown like subdomain.site.com/images/etc/img.jpg but the content will actually be on site.com/websites/subdomain.site.com/images/etc/img.jpg

Sorry for creating multiple questions, the docs is hard for me i'm totally new to this but im trying... please help with this :)

RewriteEngine on
RewriteBase /
RewriteCond %{REQUEST_URI} !^/websites/
RewriteCond %{HTTP_HOST} (.*)$ [NC]
RewriteRule ^(.*)$ /websites/%1/ [L]
ErrorDocument 404 /

Answer 1

Your .htaccess is quite close to what you want. You just need to use $1 as well as shown:

RewriteEngine on
RewriteBase /
RewriteCond %{REQUEST_URI} !^/websites/
RewriteCond %{HTTP_HOST} ^(.*)$ [NC]
RewriteRule ^(.*)$ /websites/%1/$1 [L]
ErrorDocument 404 /

%1 only refers to the domain matched in RewriteCond.
$1 is required to refer the rest of the URL matched in ReqwriteRule.

EDIT: To exclude www. and site.com

RewriteEngine on
RewriteBase /
RewriteCond %{HTTP_HOST} !^(www\.)?(site\.com)$ [NC]
RewriteCond %{REQUEST_URI} !^/websites/
RewriteCond %{HTTP_HOST} ^(.*)$ [NC]
RewriteRule ^(.*)$ /websites/%1/$1 [L]
ErrorDocument 404 /

Answer 2

Consider "subdomain" is a folder inside ur website then try this below code

RewriteEngine on
RewriteBase / 

#if not already subdomain.website.com
RewriteCond %{HTTP_HOST} !^subdomain\.website\.com$ [NC] 
#if request is for subdomain/, go to subdomain.website.com
RewriteRule ^subdomain/$ http://subdomain.site.com [L,NC,R=301]