nix-channel --list #<output> nixpkgs https://nixos.org/channels/nixpkgs-unstable The command returns a name for each channel (e.g., nixpkgs) and an URL. Note When running nix-env with the parameter -A, one can select the channel to get the package from. Such a command looks like nix-env -iA channelname.packagename.
Instead of #<output> it should have said channel-name instead at the top nix-channel example to keep it consistent.
However, using channels is not fully reproducible, as a channel may evolve to incorporate updates.
TODO: Find other sources about this topic. I remember this mentioned already (and it makes) sense, but need to learn more.
TODO: What is a better alternative? An own repo? Flakes? Can cachix help?
It says right below that pinning can help but keep looking.
When package reproducibility become a major concern, as it is the case in this tutorial, it is preferable to refer to a pinned version of the nixpkgs repository instead — i.e, a specific commit of the repository or an immutable archived tarball. The ability to pin the version of nixpkgs is powerful, it will ensure that a package is always constructed from the same Nix source. As we go deeper in the tutorial we avoid using channels in favor of pinned environments.
However, it makes the “Making the package available to the user” more complex. Nix heavily relies on environment variables to make this possible
And symlinks
Even if this is possible, we chose not to use Nix to store the experiment input and output data in this tutorial.
How?