I think one thing that's interesting about "temporary" installation is that nix has this notion of "present" vs "installed." When you run a nix-shell the progr

I think one thing that's interesting about "temporary" installation is that nix has this notion of "present" vs "installed." When you run a nix-shell the program is downloaded and if necessary built and put into the nix store, after leaving the shell it's all right there on your disk ("present") just not "installed" into the environment. This is why the first time you run nix-shell with something new it downloads stuff while subsequent invocations are immediate. It also means that if you liked ripgrep in a shell, installing it is just has nix write out some new symlinks.