When comparing rsync vs bup, the Slant community recommends rsync for most people. In the question“What are the best backup programs for Linux?” rsync is ranked 3rd while bup is ranked 11th. The most important reason people chose rsync is:
Only the changed parts of files are synced. For instance, if a long log file increases by just a few lines of text, a small diff will be sent to and saved in the archive. Rsync also compresses data in transit.
Specs
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Pros
Pro Fast and bandwidth efficient
Only the changed parts of files are synced. For instance, if a long log file increases by just a few lines of text, a small diff will be sent to and saved in the archive. Rsync also compresses data in transit.
Pro Works over SSH
SSH support allows sending files securely over the network by encrypting all communcation.
Pro Pre-installed on OSX and most Linux distributions
Many *nix systems bundle rsync so there's nothing to install. All you need to do is open up the terminal and start using rsync.
Pro Free and open source
Licensed under GNU.
Pro Saves only the minimum amount of data needed
Data is shared between different incremental backups without having to know which backup is based on which. Even for backups that come from different computers that know nothing about each other. Bup simply saves the minimal amount of data needed.
Pro Huge files can be backed up incrementally
Bup splits up files into different chunks. This is especially useful for large files which can then be stored without using a lot of disk space for different versions of the same file.
Cons
Con No official GUI
To use rsync, you have to know your way around the command line.
Con Complicated, and you can accidentally overwrite the wrong files
Con No GUI
Only available as a command line tool.