I am new to ubuntu , i have installed rdiff-backup.

I have folder called sqlfiles on remote ftp server.The sql filesa are stored for last three days and then deleted. But i want to download the all copies to local computers

I want to have incremental backups on my local server so that

1)If file is same then it should not be copied 2)if different , then overwrite it 3)If file is in local directory and not in FTP , then leave as it is

How can i apply those rules to r-diff