NixOS (Nix Operating System) is a Linux distribution with a powerful configuration and package manager. It comprises the Nix package management utility that runs on top of the NixOS operating system. The main command for installing and managing packages is `nix-env`. It allows root and non-root users to install, upgrade and uninstall packages. It also allows users to view installed packages, roll back and switch between different generations. Packages installed by root users are available ......