[OscarCunningham]

I recently installed NixOS on my laptop after years of using Debian, and the main difference I noticed was that it's much easier to keep everything clean.

For example with Debian I might do something like try to get my GPU to work by installing nouveau, try various configs, then uninstall nouveau and install the Nvidia proprietary drivers. But then when I finally got the GPU working, I'd worry. Are some of those config changes I tried for nouveau still affecting my system? Has all that mucking around left my GPU forever in a suboptimal state?

With Nix, it might take just as much tinkering to get the GPU to work. But once I'm done, I know that my system is exactly as I've defined it in configuration.nix. Anything else I tried along the way will just sit inertly in /nix/store until the garbage collector wipes it away.

[layer8]

I don’t know. My concept for reproducibility with Debian is a backup of /etc and the list of installed packages (the output of `dpkg --get-selections`). It’s also not difficult to diff one’s /etc with a pristine version, though I haven’t actually needed that in many years.

[__MatrixMan__]

If that scratches the itch, great. Backups of /etc can't be combined in a way that lets you reliably uncombine them later though, so you're going to be limited in how modular you can make it.

[layer8]

That’s true, though using version control with branches and merges can get you pretty far.

[OscarCunningham]

I believe 'dpkg --get-selections' lists all packages, not just the ones the user installed. So if I installed some package foo that had a dependency bar, this method would have me carrying around bar even if foo updated to stop depending on it.

[layer8]

You are right. In that case, apt-clone is better, though not universally available.

[pabs3]

The Debian cruft-ng package, plus package list diffs, can identify problematic state you have added to the system.