NixOS – How to Search for Packages in a Specific Channel

nixnixos

nix-env -v -qaP '*' currently returns all the packages available from all my channels.

How can I specify to return packages from a specific channel for example unstable / 18.03?

nix-env -f "https://github.com/NixOS/nixpkgs-channels/archive/775fb69ed73e7cf6b7d3dd9853a60f40e8efc340.tar.gz" -qa '*'

I grabbed the commit from selecting the branch on github: https://github.com/NixOS/nixpkgs/tree/nixos-19.03

you can use nix-env tool

% nix-env -f https://github.com/NixOS/nixpkgs-channels/archive/nixos-unstable.tar.gz -iA tig

or use nix-build tool

% nix-build -I nixpkgs=https://github.com/NixOS/nixpkgs-channels/archive/nixos-unstable.tar.gz -A tig

how that helps!

This file is indeed specific to NixOS and it is created automatically when installing NixOS. That said, there are workarounds.

One of them is described in https://nixos.org/nixpkgs/manual/#sec-declarative-package-management in the Nixpkgs manual. (Added in this PR.)

Please note that the overlays mechanism came along since then, and according to Chapter 12. Overlays: "Overlays are similar to other methods for customizing Nixpkgs, in particular the packageOverrides attribute described in Section 6.5, “Modify packages via packageOverrides”. Indeed, packageOverrides acts as an overlay with only the super argument. It is therefore appropriate for basic use, but overlays are more powerful and easier to distribute."
It seems that there was also a work-in-progress for a user-side declarative configuration but it hasn't been updated in a while: https://github.com/NixOS/nixpkgs/pull/9250
See also the Declarative package management for normal users discussion on the NixOS Discourse.