There a times when you need to build something from the nix unstable channel. For example the master contains a new package you need, but the next nixpkgs release is somewhere in the future, and you need this package now. In this guide I want to show how to install packages from unstable by using nix-env. Furthermore I hope to give a basic understanding of the channels concept.
A channel is a set of expressions which includes severall build, installation and configuration instructions for packages, services and the system itself. The repository normaly used here is nixpkgs. It is developed at https://github.com/NixOS/nixpkgs.
The unstable channel is a copy of the NixOS/nixpkgs master. It is pulled from github once in a while and will be available from a mirror under https://nixos.org/channels/nixpkgs-unstable. Since NixOS uses half-anual released stable channels, some changes (especially new f