why won't my rewriteRule work?

I have my document roots set to:

  DocumentRoot "/opt/bitnami/apache2/htdocs"

  <Directory "/opt/bitnami/apache2/htdocs">  in both the 80 and 443 areas of bitnami.conf, which is just like .htaccess. 

in my config.php I have $config['base_url']='https://www.rdsubstantiation.com/sub_crud/';
in my routes.php I have:

$route['default_controller'] = 'Users/login';
$route['404_override'] = '';
$route['translate_uri_dashes'] = FALSE;
$route['registration'] = 'registration';
$route['login'] = 'login';
$route['subit_backend']['GET']='subit_backend/register';

This all seems to work perfectly since my application sits in /sub_crud/

The problem is that a user can go to https://www.rdsubstantiation.com and they will see a "Welcome to Bitnami message".

Bitnami doesn't use .htaccess, they use bitnami.conf instead. I thought I could use:

RewriteRule "www.rdsubstantiation.com" "https://www.rdsubstantiation.com/sub_crud" [R,L]

in bitnami.conf to force a user at rdsubstantiation.com to rdsubstantiation.com/sub_crud. But it doesn't seem to work. What am I doing wrong or it there a better way just to block www.rdsubstantiation.com???

proof that an old dog can learn new tricks

I have my document roots set to:

  DocumentRoot "/opt/bitnami/apache2/htdocs"

  <Directory "/opt/bitnami/apache2/htdocs">  in both the 80 and 443 areas of bitnami.conf, which is just like .htaccess. 

in my config.php I have $config['base_url']='https://www.rdsubstantiation.com/sub_crud/';
in my routes.php I have:

$route['default_controller'] = 'Users/login';
$route['404_override'] = '';
$route['translate_uri_dashes'] = FALSE;
$route['registration'] = 'registration';
$route['login'] = 'login';
$route['subit_backend']['GET']='subit_backend/register';

This all seems to work perfectly since my application sits in /sub_crud/

The problem is that a user can go to https://www.rdsubstantiation.com and they will see a "Welcome to Bitnami message".

Bitnami doesn't use .htaccess, they use bitnami.conf instead. I thought I could use:

RewriteRule "www.rdsubstantiation.com" "https://www.rdsubstantiation.com/sub_crud" [R,L]

in bitnami.conf to force a user at rdsubstantiation.com to rdsubstantiation.com/sub_crud. But it doesn't seem to work. What am I doing wrong or it there a better way just to block www.rdsubstantiation.com???

For those of you have been trying to help find a solution for this beginners question, I found the answer. This was supplied by a bitnami engineer: RewriteRule "^/$" "/sub_crud/" [R,L]. I know that ^ is ends with and $ is begins with. 

proof that an old dog can learn new tricks