Nix Pills - Chapter 3 - Enter the Environment⚓︎
The closures of a derivation is a list of all its dependencies, recursively, including absolutely everything necessary to use that derivation. To view all of a derivations dependencies you can use nix-store -q --tree $(which man). Copying all of these derivations with nix-copy-closures or nix-store --export to the Nix store of another machine makes it able to run man out of the box on the other machine.
Channels are a set of packages and expressions available for download. There are numerous channels from which Nix and NixOS can get packages, although usually only a single channel is needed. nix-channel helps manage installed channels, and nix-channel --list will show the current installed channels. nix-channel --update will update installed channels, similar to apt update on Ubuntu.
