a powerful package manager for Linux and other Unix systems
that makes package management reliable and reproducible. It
provides atomic upgrades and rollbacks, side-by-side installation
of multiple versions of a package, multi-user package management
and easy setup of build environments.
NixOS is a Linux distribution with a unique approach
to package and configuration management. Built on top of the
Nix package manager, it is completely declarative, makes
upgrading systems reliable, and has
many other advantages.