Updating NixOS
1. Introduction
NixOS stands out due to its declarative configuration and atomic updates, which ensure that system updates are predictable, reversible, and don’t risk breaking the setup. This approach guarantees consistency across versions, allowing any changes to be easily rolled back. NixOS also offers flexibility, multi-version support, and advanced dependency management, making it an excellent choice for developers and system administrators.
As part of this process, only repository channels are updated or removed during updates. The system requires an internet connection to download the latest changes, and users cannot directly modify the system. For optimal stability, security, and access to new features, regular updates — ideally once a week — are recommended.
All commands below are executed in a Terminal application (Shell: Bash).
2. Rebuilding the system after editing configuration.nix file
If you want to apply the configuration changes made in /etc/nixos/configuration.nix without updating the channels, Nixpkgs and package versions. This is typically used when you've edited the system configuration, and you just want to apply those changes:
sudo nixos-rebuild switch
3. Updating channels and rebuilding the system
3.1 Updating NixOS channels
sudo nix-channel --update
3.2 Rebuilding the system after updating channels
If you want to not only apply your configuration changes but also update the packages and system environment to the latest versions available from the Nixpkgs repository. This is typically used when you want to ensure you are using the latest versions of your software and system services:
sudo nixos-rebuild switch --upgrade
4. Changing Nixpkgs version
5. Deleting old generations
sudo nix-collect-garbage -d
6. Summary: Automating system updating and deleting old generations
sudo nix-channel --update && sudo nixos-rebuild switch --upgrade && sudo reboot