Redirect for specific links. Problem with RewriteRule

Question

Regular Expressions

Hello.
I ask you to help with the correct formulation of the condition in .htaccess.
In a nutshell :
The site mysite.ru (Site 1) had its domain name changed to http://old.mysite.ru, and the name mysite.ru was assigned to a new site (Site 2).
Part of the materials from Site 1 was not transferred to Site 2, and the task is to ensure that these materials indexed by search engines with links like " http://mysite.ru/content/view/any_integer_number/11/ " open, but, of course, already on links like " http://old.mysite.ru/content/view/any_integer_number/11/ "
At the root of Site 2 in .htaccess I write:

RewriteEngine On
RewriteCond %{HTTP_HOST} ^mysite\.ru\/content\/view\/([0-9]+)\/11\/$ [NC]
RewriteRule ^(.*)$ http://old.mysite.ru/content/view/$1/11/ [L]

But, you see, something was too clever with the syntax and redirection does not occur.
Give me the right idea, please.

Answer 1

You will never have such an HTTP_HOST, use THE_REQUEST

Answer 2

Options +FollowSymLinks
RewriteEngine On
RewriteCond %{HTTP_HOST} ^mysite\.ru$ [NC]
RewriteRule ^(.*)$ old.mysite.ru/$1 [R=301,L]
Redirect from mysite.ru to old.mysite. ru. If the first two lines are uncommented, then they do not need to be written again.

Answer 3

Get the working code.

RewriteEngine On
RewriteCond %{REQUEST_URI} /content/view/([0-9]+)/11/$ [NC]
RewriteRule ^(.*) http://old.mysite.ru/$1 [R=301,L]

HTTP_HOST - returns mysite.ru, www.mysite.ru, subdomain.mysite.ru. REQUEST_URI - Returns everything after the domain.
Backslashes before slashes are not needed.