alt Hacker News>But what is "atomic and transactional Linux"?
It's a glorified Live CD, with added "persistence" for user data. Updates are done by replacing the system install (which is readonly during normal operation, just like a Live CD) and rebooting, with an A+B mechanism enabling seamless updates during operation, as well as rollback if the new install fails. It's the modern "cattle not pets" approach to system administration: every system is running a well-defined ("atomic") Live CD equivalent, not something bespoke that's the unpredictable result of partial updates and/or edits on the running system.
No, updates are done by creating a snapshot of the read only mounted root, and applying the packages via the usual package manager in there. The snapshot only becomes active at reboot, and if starting fails it'll revert automatically back to the last known working snapshot for the next boot.
Things like /etc are writeable, so you don't need to reboot for simple configuration changes.
You can run it just like always with all packages installed - it's just not recommended as the additional complexity on updates increases the risk that manual intervention is needed, and tooling is good enough that for a lot of stuff you don't really need it there. Like, toolbox or distrobox as podman based containers running in the host namespace (either as user or root), allowing persistent installation of debug tools, without having to reboot.