intro

Nix is a powerful package manager for Linux and other Unix systems that makes package management reliable and reproducible. It uses Nix language to declare packages and configurations to be built by Nix.

Nix uses a single directory to store packages and all other stuff related to it. Packages in Nix are stored in directories such as

/nix/store/jibjl4rxy9cnmwcmsglwfk6f2azh4gll-firefox-107.0/
├── bin
│   └── firefox
├── lib
│   ├── firefox
│   │   └── ...
│   └── mozilla
│       └── ...
└── share
    ├── applications
    │   └── firefox.desktop
    └── icons
        └── ...

where the hash jibjl... is a unique identifier for the package which takes into account package build settings and all its dependencies. Notice the directories bin, lib, and share which we usually in the root directory / in Linux and BSD systems.

The way Nix manages packages allows you to have multiple versions of the same software installed at the same time without any conflict once each package is packaged with all its dependencies. Obviously, it increases storage, but is also allows one to switch between packages or rollback in case you don't like an upgrade with a simple command.

install Nix

There are two ways to install Nix, single and multi-user. Nix recommends multi-user installation and lists the pros and cons of this method.

My choice when I did install it on a Debian machine for the first time was the single-user method because I was the only user on that machine and the uninstall process is easy as running rm -rf /nix.

Detailed information about each method can be found on Nix manual.

Single-user installation:

$ sh <(curl -L https://nixos.org/nix/install) --no-daemon

Multi-user installation:

$ sh <(curl -L https://nixos.org/nix/install) --daemon

using Nix

search for a package

$ nix-env -qaP firefox
nixpkgs.firefox-esr          firefox-102.5.0esr
nixpkgs.firefox-esr-wayland  firefox-102.5.0esr
nixpkgs.firefox              firefox-107.0
nixpkgs.firefox-wayland      firefox-107.0
nixpkgs.firefox-esr-91       firefox-91.13.0esr

Nix allows you to can use regex

$ nix-env -qaP 'firefox.*'

install a package

$ nix-env -iA nixpkgs.firefox
installing 'firefox-107.0'
...

"uninstall" a package

$ nix-env -e firefox
uninstalling 'firefox-107.0'

This only makes the package unavailable to the user. Please read Nix quirks below.

upgrade all packages

$ nix-channel --update
$ nix-env -u

Nix quirks

garbage collection

Uninstalling a package in Nix does not delete it from your disk as you could, for example, rollback the system to the previous state. As storage is not always enough as we wish, we need to actually delete those unused packages and Nix knows how to do it without breaking anything.

The Nix utility nix-collect-garbage deletes all packages that aren’t in use by any user profile or by a currently running program. You can run the garbage collector after every uninstall, but you will lose the great rollback functionality of Nix.

nix-shell

Nix also allows you to test a package in a temporary shell environment with nix-shell:

[adriano@laptop:~]$ nix-shell -p jupyter
...
[nix-shell:~]$ jupyter-notebook

All packages downloaded for use in this temporary environment remain on your disk after you finish the use and will only be deleted on the next garbage collection unless you actually install it.

acknowledgments

Thanks to @solene@bsd.network, @n0r@sueden.social, @thedaemon@socel.net and @distrotube@fosstodon.org for the debate on Mastodon which made me write this post.

get in touch

• Email

  hi@adrianobarbosa.xyz