Linux installs (apart from grub boot blocks and partitioning) are JBOF (just a bunch of files). Mostly, the non-user parts are /etc /boot /usr and /var (for pa

Linux installs (apart from grub boot blocks and partitioning) are JBOF (just a bunch of files). Mostly, the non-user parts are /etc /boot /usr and /var (for package management), and things aren't always in the same places and conf files may vary in options because of version/patch differences. Using symlinks and seperate directories, it's theoretically possible to switch OSes at boot time assuming everything is symlink-agonistic (stow for operating systems) It's possible and rarely necessary except for personal playgrounds but a production box would follow 12factors standards and lifecycle the entire OS by switching the underlying base image with something like unionfs + hypervisor. Lots of ways to shoot yourself in the feet, and in box rebuilds it's usually much faster to just start fresh and deploy using configuration management than try to hammer a bank into the shape of plane. Definitely make verified backups before attempting a lobotomy on anything real.