> immutability is a lie, many parts of the systems are mutable, although I don't know how to describe this family with a different word (transactional something?).
In the case of Nix, it sounds like it's more focused on reproduce-ability? It sounds like I should be able to take the Nix configuration file, plop it on another computer, and get the same system (except, perhaps, for /home).
Some of the others sound more like existing tools that provide snapshot/rollback capability, just with different implementations.
That's a atomic transaction, like a database. Although having to shut down the system to do a commit is a bit much.
Microsoft put atomic transactions into their file system years ago, but file system transactions were never used much. You'd like to have an install system where all changes commit all at once, and if anything goes wrong during install, nothing commits and you roll back to the previous state. In theory a transactional file system could do that. In practice, there's probably too much other non file systems state involved.
In the case of Nix, it sounds like it's more focused on reproduce-ability? It sounds like I should be able to take the Nix configuration file, plop it on another computer, and get the same system (except, perhaps, for /home).
Some of the others sound more like existing tools that provide snapshot/rollback capability, just with different implementations.