The Nix Packages collection (Nixpkgs) is a set of thousands of packages for the Nix package manager, released under a permissive MIT/X11 license. Packages are available for several platforms, and can be used with the Nix package manager on most GNU/Linux distributions as well as NixOS.
This manual primarily describes how to write packages for the Nix Packages collection (Nixpkgs). Thus it’s mainly for packagers and developers who want to add packages to Nixpkgs. If you like to learn more about the Nix package manager and the Nix expression language, then you are kindly referred to the Nix manual. The NixOS distribution is documented in the NixOS manual.
Nix expressions describe how to build packages from source and are collected in the nixpkgs repository. Also included in the collection are Nix expressions for NixOS modules. With these expressions the Nix package manager can build binary packages.
Packages, including the Nix packages collection, are distributed through
channels. The collection is
distributed for users of Nix on non-NixOS distributions through the channel
nixpkgs. Users of NixOS generally use one of the
nixos-* channels, e.g.
nixos-19.09, which includes all packages and modules for the stable NixOS
19.09. Stable NixOS releases are generally only given
security updates. More up to date packages and modules are available via the
nixpkgs follow the
master branch of the Nixpkgs
repository, although both do lag the
master branch by generally
a couple of days. Updates to a channel are
distributed as soon as all tests for that channel pass, e.g.
shows the status of tests for the
The tests are conducted by a cluster called Hydra,
which also builds binary packages from the Nix expressions in Nixpkgs for
The binaries are made available via a binary cache.
The current Nix expressions of the channels are available in the
nixpkgs repository in branches
that correspond to the channel names (e.g.