Matthew BauerBlogRSS

23 Feb 2019

Static Nix: a command-line swiss army knife

Nix is an extremely useful package manager. But, not all systems have it installed. Without root priveleges, you cannot create the /nix directory required for it to work.

With static linking, and some new features added in Nix 2.0, you can fairly easily use the Nix package manager in these unpriveleged context1. To make this even easier, I am publishing prebuilt a x86_64 binary on my personal website. It will reside permanently at https://matthewbauer.us/nix (5M download).

1 Trying it out

You can use it like this,

$ curl https://matthewbauer.us/nix | sh -s run --store $HOME/.cache/nix/store -f channel:nixpkgs-unstable hello -c hello
Hello World!

You can use any package provided by Nixpkgs (using the attribute name). This gives you a swiss army knife of command line tools. I have compiled some cool commands to try out. There examples of various tools, games and demos that you can use through Nix, without installing anything! Everything is put into temporary directories2.

1.1 Dev tools

$ nix=$(mktemp); \
  curl https://matthewbauer.us/nix > $nix && \
  chmod +x $nix && \
  $nix run --store $HOME/.cache/nix/store -f channel:nixpkgs-unstable \
  bashInteractive curl git htop imagemagick file findutils jq nix openssh pandoc

1.2 Emacs

$ nix=$(mktemp); \
  curl https://matthewbauer.us/nix > $nix && \
  chmod +x $nix && \
  $nix run --store $HOME/.cache/nix/store -f channel:nixpkgs-unstable \
  emacs -c emacs

1.3 File manager

$ nix=$(mktemp); \
  curl https://matthewbauer.us/nix > $nix && \
  chmod +x $nix && \
  $nix run --store $HOME/.cache/nix/store -f channel:nixpkgs-unstable \
  ranger -c ranger

1.4 Fire

$ curl https://matthewbauer.us/nix | \
  sh -s run --store $HOME/.cache/nix/store -f channel:nixpkgs-unstable \
  aalib -c aafire

1.5 Fortune

$ curl https://matthewbauer.us/nix | \
  sh -s run --store $HOME/.cache/nix/store -f channel:nixpkgs-unstable \
  bash cowsay fortune -c sh -c 'cowsay $(fortune)'

1.6 Nethack

$ nix=$(mktemp); \
  curl https://matthewbauer.us/nix > $nix && \
  chmod +x $nix && \
  $nix run --store $HOME/.cache/nix/store -f channel:nixpkgs-unstable \
  nethack -c nethack

1.7 Weather

$ curl https://matthewbauer.us/nix | \
  sh -s run --store $HOME/.cache/nix/store -f channel:nixpkgs-unstable \
  bash curl cowsay -c sh -c 'cowsay $(curl wttr.in/?format=3)'

1.8 World map

$ curl https://matthewbauer.us/nix | \
  sh -s run --store $HOME/.cache/nix/store -f channel:nixpkgs-unstable \
  bash coreutils curl libcaca ncurses -c bash -c \
  'img=$(mktemp ${TMPDIR:-/tmp}/XXX.jpg); \
  curl -k https://www.cia.gov/library/publications/the-world-factbook/attachments/images/large/world-physical.jpg > $img \
  && img2txt -W $(tput cols) -f utf8 $img'

1.9 Youtube

$ curl https://matthewbauer.us/nix | \
  sh -s run --store $HOME/.cache/nix/store -f channel:nixpkgs-unstable \
  bash youtube-dl mplayer -c sh -c \
  'mplayer -vo caca $(youtube-dl --no-check-certificate -g https://www.youtube.com/watch?v=dQw4w9WgXcQ)'

1.10 And more…

Lots more cool things are possible. Look through the packages provided by Nixpkgs if you need inspiration.

2 Avoid installing and extracting each time

This method of using Nix has some upfront cost. This is because https://matthewbauer.us/nix must be downloaded each time and the embedded .tar.gz file extracted. If you want Nix to stay around permanently, you have to follow a few tricks. Total install size is about 11M. Using this method, you will reduce startup and keep Nix in your path at each login.

I have two ways of doing this. One the “easy” way is just running this script.

$ curl https://matthewbauer.us/nix.sh | sh

The other is the “safe” way and involves running some commands in order. These are the same commands run by the script, but this lets you audit everything being done line by line.

$ t=$(mktemp -d)
$ curl https://matthewbauer.us/nix > $t/nix.sh
$ pushd $t
$ sh nix.sh --extract
$ popd
$ mkdir -p $HOME/bin/ $HOME/share/nix/corepkgs/
$ mv $t/dat/nix $HOME/bin/
$ mv $t/dat/share/nix/corepkgs/* $HOME/share/nix/corepkgs/
$ echo export 'PATH=$HOME/bin:$PATH' >> $HOME/.profile
$ echo export 'NIX_DATA_DIR=$HOME/share' >> $HOME/.profile
$ source $HOME/.profile
$ rm -rf $t

You can now run the Nix commands above as you need to, and it will be available on each login. Remember to always add the arguments -f channel:nixpkgs-unstable and --store $HOME/.cache/nix/store, otherwise Nix will be confused on how to handle the missing /nix/store and other environment variables.

3 Build it yourself

This is certainly a security vulnerability so you may want to build static Nix for youself from my pull request. Of course you can’t build static Nix without Nix, so this would need to be done from a system that has Nix installed. You can build it yourself, provided you have git and nix installed, like this,

$ git clone https://github.com/matthewbauer/nixpkgs.git
$ cd nixpkgs
$ git checkout static-nix
$ nix-build -A pkgsStatic.nix

Then, copy it to your machine without Nix installed (provided you have ssh installed), like this,

$ scp ./result/bin/nix your-machine:
$ ssh your-machine
$ ./nix ...

Footnotes:

1

Note that you will need to be able to set up a private namespace. This is enabled by default on Linux, but some distros have specifically disabled it. See this issue for more discussion.

2

While ideally we would not need temporary directories at all, some of these commands require it. This is because they check whether they are in a pipe and refuse to run if so. Your temporary directory should be cleaned each time your reboot anyway. The Nix packages will be installed in $HOME/.cache/nix/store but they can be removed at any time.

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