How to move a char from the subdomain to the filename in Apache mod rewrite?

I have this URL:

http://hostX.site.com/some_path_here/filename.jpg

and need to rewrite it to:

http://host.site.com/same_path_here/filenameX.jpg

Can you please tell me if this is possible? Basically I am trying to move "X" (it is a number) from the subdomain to the end of the filename, just before the extension.

Thanks.

From stackoverflow

• (Without testing,) something like this should work:

  RewriteCond %{HTTP_HOST} host(\d).site.com
  RewriteRule (.*)\.(.*) host.site.com/$1%1.$2
  

  You need to extract the host number through the RewriteCond. In the RewriteRule you can use the number with the %-modifier

  HTH

• Something like this should do it:

  RewriteCond %{HTTP_HOST} ^host(\d)\.example\.com$
  RewriteRule (.*)\.([^/.]+)$ http://host.example.com/$1%1.$2
  

  But since the host is different, this will cause an external redirect.