How to intercept a GET request to an existing file via htaccess?

Question

htaccess

Can you please tell me how can I intercept a certain get request to an existing file and redirect it to another using htaccess?
For example, on request /dir/one.php? get =1 return /dir/two.php? get =1, and for any other request, return the first file as well.

Answer 1

RewriteCond %{QUERY_STRING} ^(get=1)$
RewriteRule ^/dir/one.php$ /dir/two.php?%1