Hotwire is an object-oriented hypershell. It is a shell designed for systems programming (files, processes), and thus it is in the same conceptual category of software as the Unix shell+terminal and Windows PowerShell.
rdiff-backup backs up one directory to another, possibly over a network. The target directory ends up a copy of the source directory, but extra reverse diffs are stored in a special subdirectory of that target directory, so you can still recover files los