Rsync

wp:rsync is a utility for efficiently transferring and synchronizing files across computer systems, by checking the timestamp and size of files; and optionally a checksum comparison. It is commonly found on Unix-like systems and functions as both a file synchronization and file transfer program. The rsync algorithm is a type of delta encoding, so that only file differences are transmitted across the network. Zlib may be used for additional compression, and SSH or stunnel can be used for data transport security.