mirror of https://github.com/NixOS/nix.dev.git synced 2024-10-18 14:32:43 -04:00

Yuki Langley ac06c07360 Make code blocks consistent

Illustration of shell sessions or terminals should use shell-session.

Entire expressions should be encapsulated in code blocks, not inline code.

2022-11-08 17:37:41 +01:00

(ref-pinning-nixpkgs)=

Pinning Nixpkgs

Different ways:

As environment variable: $NIX_PATH=URL
-I command line parameter to most of commands like nix-build, nix-shell, etc
Using builtins.fetchTarball function that fetches the channel at evaluation time

Possible `URL` values

Local file path. Using just . means that nixpkgs is located in current folder.
Pinned to a specific commit: https://github.com/NixOS/nixpkgs/archive/addcb0dddf2b7db505dae5c38fceb691c7ed85f9.tar.gz
Using latest channel, meaning all tests have passed: http://nixos.org/channels/nixos-21.05/nixexprs.tar.xz
Using latest channel, but hosted by github: https://github.com/NixOS/nixpkgs/archive/nixos-21.05.tar.gz
Using latest commit for release branch, but not tested yet: https://github.com/NixOS/nixpkgs/archive/release-21.05.tar.gz

$ nix-build -I nixpkgs=http://nixos.org/channels/nixos-21.05/nixexprs.tar.xz`

$ NIX_PATH=nixpkgs=http://nixos.org/channels/nixos-21.05/nixexprs.tar.xz nix-build ...`

Using just Nix:

let
  pkgs = import (fetchTarball "https://github.com/NixOS/nixpkgs/archive/nixos-21.05.tar.gz") {};
in pkgs.stdenv.mkDerivation { ... }

To make ad-hoc environment available on NixOS:

{
  nix.nixPath = [ ("nixpkgs=" + toString pkgs.path) ];
}