Pinning Nixpkgs

Specifying remote Nix expressions, such as the one provided by Nixpkgs, can be done in several ways:

• $NIX_PATH environment variable

• -I option to most of commands like nix-build, nix-shell, etc.

• fetchurl, fetchTarball, fetchGit or Nixpkgs fetchers in Nix expressions

Possible URL values

• Local file path:

  ./path/to/expression.nix
  

  Using ./. means that the expression is located in a file default.nix in the current directory.

• Pinned to a specific commit:

  https://github.com/NixOS/nixpkgs/archive/eabc38219184cc3e04a974fe31857d8e0eac098d.tar.gz
  

• Using the latest channel version, meaning all tests have passed:

  http://nixos.org/channels/nixos-22.11/nixexprs.tar.xz
  

• Shorthand syntax for channels:

  channel:nixos-22.11
  

• Using the latest channel version, hosted by GitHub:

  https://github.com/NixOS/nixpkgs/archive/nixos-22.11.tar.gz
  

• Using the latest commit on the release branch, but not tested yet:

  https://github.com/NixOS/nixpkgs/archive/release-21.11.tar.gz
  

Examples

• $ nix-build -I ~/dev
  

• $ nix-build -I nixpkgs=http://nixos.org/channels/nixos-22.11/nixexprs.tar.xz
  

• $ nix-build -I nixpkgs=channel:nixos-22.11
  

• $ NIX_PATH=nixpkgs=http://nixos.org/channels/nixos-22.11/nixexprs.tar.xz nix-build
  

• $ NIX_PATH=nixpkgs=channel:nixos-22.11 nix-build
  

• In the Nix language:

  let
    pkgs = import (fetchTarball "https://github.com/NixOS/nixpkgs/archive/nixos-22.11.tar.gz") {};
  in pkgs.stdenv.mkDerivation { ... }
  

Finding specific commits and releases

status.nixos.org provides:

• Latest tested commits for each release - use when pinning to specific commits

• List of active release channels - use when tracking latest channel versions

The complete list of channels is available at nixos.org/channels.

Tip

More information on Nixpkgs and NixOS releases: Which channel branch should I use?