How to change domain via .htaccess?

Question

htaccess

Hello!
For a very long time I can not solve one problem and understand what's wrong.
The point is that I need to redirect requests to one domain like:
example.com → example.ru
example.com/page → example.ru/page
sub.example.com → sub.example.ru
sub.example.com/ test
→ sub.example.ru/test if the domain is not example.ru, then we apply the rules to make the domain the way it should be.
I searched for a long time and even seemed to find a solution, but for some reason it does not work (no redirects occur):
RewriteCond %{HTTP_HOST} !example\.ru$
RewriteCond %{HTTP_HOST} ^([^.]+\. )?example\.
RewriteRule ^ http://%1example.ru%{REQUEST_URI} [NC,L,R=301]
If I comment on the second line, it starts working, but without subdomains.
So far I have settled on my decision:
RewriteCond %{HTTP_HOST} !([^.]+\.)?example.ru$ [NC]
RewriteRule ^ http://example.ru%{REQUEST_URI} [R=301,L]
Please Your help and thanks in advance!