Redirecting user to a folder but show another domain

I am using htaccess to redirect people from a domain that is registered on开发者_如何学C my host to a folder. Ex: the user type www.my2nddomain.com and I redirect them to www.my1stdomain.com/folder. But I wanted to show the domain the user typed instead of the address with the folder on it. How do I do it? Thanks in advance!

If the folder is on the same machine then you can just point them to the folder on the filesystem and omit the R flag. If the folder is on a completely different machine then you'll need to make sure mod_proxy is enabled and use the P flag.