csync - A professional file synchronizer for normal users

sync is a lightweight utility to synchronize files between two directories on a system or between multiple systems. It synchronizes bidirectionally and allows the user to keep two copies of files and directories in sync. csync uses widely adopted protocols, such as smb or sftp, so that there is no need for a server component. It is a user-level program which means you don’t need to be a superuser or administrator.