A package in NixOS can have multiple programs or none of them. It can be a library for other programs.
$ nix-shell -p cowsay --run "cowsay nix"
The code indicating that the package cowsay contains a binary which will run the code with argument "cowsay nix"
- The Lookup Paths is where path packages are found.
Pinning Packages
- use a commit
- status: nixos.org
- stable: nixos-21.05 example
- unstable: nixos-unstable
{pkgs ? import (fetchTarball "https://github.com/nixos/nixpkgs/archive/06278c77bsd162e62df170fec307c83f1812d94b.tar.gz") {} }: