this post was submitted on 16 Jun 2023
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Linux
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Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).
Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.
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Your whole system is defined in a file called
configuration.nix. This file describes everything about your system: all packages installed, which Desktop Environment / Window Manager to use, and also configuration for almost everything (e.g. zsh or neovim). When "switching" (which is basically installing/updating the system), Nix looks at the configuration and changes your system according to what you've declared in theconfiguration.nix, installing or uninstalling packages for instance.So, the state of your system is "declared" in a single file, which can be tracked in git or backed up wherever. If you have mulitple systems, you can also share parts of your config between them, which makes configuring and customizing stuff a lot easier.
There are a lot of other aspects, but thats the basic gist of it
That sounds really cool… so you could just take that file, do a clean install of nix, then put that file back and it’ll install all your old packages and stuff?
Basically yes
you could also go so far as to wipe your root partition (except for some selected dirs) on every boot, although I don't do that myself: https://github.com/nix-community/impermanence
Not just your packages, but all your config as well.
Also, I believe updates are transactional, so if something goes wrong in the middle it can just abort and your system isn't left in an inconsistant state. And if an update breaks something you can easily roll back to a previous version.
Is it a big learning curve? Is this the emacs equivalent of OS configuration/installation?
edit: another question - Could I play around with it by installing in qemu and if I like that, take my configuration.nix from qemu and install it as my main OS?
I'd say it's a pretty steep curve unfortunately, and nixOS is also not perfect, mind you
/nix. Packages installed with nix are patched to work that way, but things not installed with it might not run out of the boxAs for trying it out, yeah copying the config from the vm should work (except for maybe some hardware-specific stuff). remember to backup your stuff just in case lol
It's really not. It has no runtime for starters; it's a pure expression language. It can't i.e. read stdin, open a socket or do an arbitrary syscall.
The end result is always data. You could and can turn every sensible evaluation of Nix into JSON.
There are indeed side-effects but they're indirect; implied by the data that is the actual end result of an evaluation of Nix expressions. If your expression evals to a derivation (data), Nix will create a .drv file for you for example. They're well defined and not arbitrary though.
Absolutely. That's how I got started ;)
If you install Nix (the package manager) on your current system, you can actually directly build a vm from a config file via
nixos-rebuild build-vm.