There’s a new kid on the backup software block: rsync. rsync was originally designed to replace rcp, the venerable old Unix remote copy program. Because of its sophisticated means of synchronizing and transferring file trees, rsync is widely used for mirroring Web sites. rsync transfers only the changes in files, using the devilishly clever rsync algorithm. It calculates diffs without needing both files to be present. This little bit of magic is described in the documentation accompanying the program (for those interested in such). rsync then does on-the-fly compression, making network file transfers very fast and efficient.

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