Nix

Nix is a purely functional package manager that aims to make package management reproducible, declarative and reliable.

Installation

Configuration

To have the Nix daemon launched at boot time, enable nix-daemon.service.

Add a channel and update it.

$ nix-channel --add https://nixos.org/channels/nixpkgs-unstable
$ nix-channel --update

Usage

With the shell configured, the following should install hello into your updated PATH:

$ nix-env -iA nixpkgs.hello

The binary itself will be located at /nix/store/[hash]-hello-[version]/bin/hello.

Run hello and make sure it is in the right PATH. If it works, you can remove it:

$ nix-env --uninstall hello

Or you can check the list of installed programs:

$ nix-env --query

You can also list generations:

$ nix-env --list-generations

See nix-env(1) for more detailed information.

Tips and tricks

Max jobs

By default, nix only uses one builder. The following will allow nix to use as many jobs as the number of CPUs:

/etc/nix/nix.conf

max-jobs = auto

Graphical acceleration

To run OpenGL and Vulkan applications, use NixGL.

Desktop integration

For integrating Nix applications with your desktop environment, add the ~/.nix-profile/share directory to your $XDG_DATA_DIRS, for instance using export XDG_DATA_DIRS=$HOME/.nix-profile/share:$XDG_DATA_DIRS.

Zsh integration for nix-shell

nix-shell starts Bash by default. zsh-nix-shell^AUR lets you use Zsh as the default shell in a nix-shell environment. Some prompt plugins such as zsh-theme-powerlevel10k^AUR and zsh-pure-prompt^AUR provide a nix-shell indicator.

Command completion

Zsh

nix-zsh-completions^AUR provides Zsh completions for nix commands such as nix-env and nix-shell.

Troubleshooting

Too many open files

Some builds may run into an error such as:

error: opening directory '/nix/store/...': Too many open files

Edit nix-daemon.service and increase the file limit:

[Service]
LimitNOFILE=65536

Warning message about root user channels

If you get this error while using Nix:

warning: Nix search path entry '/nix/var/nix/profiles/per-user/root/channels' does not exist, ignoring

The root user will need to update their channels:

# nix-channel --update

Sandbox build issues

Other sandbox issues

error: while setting up the build environment: mounting /proc: Operation not permitted
error: program '/usr/bin/nix-env' failed with exit code 1

1: package 'utils' in options("defaultPackages") was not found
2: package 'stats' in options("defaultPackages") was not found
Error: .onLoad failed in loadNamespace() for 'utils', details:
 call: system(paste(which, shQuote(names[i])), intern = TRUE, ignore.stderr = TRUE)
 error: cannot popen '/nix/store/fnkvlbls29d01jcx3wsdnhykyrl7087r-which-2.21/bin/which 'uname' 2>/dev/null', probable reason 'Cannot allocate memory'

The issue is known upstream: #2311, #3000, and #4636.

Warning It is generally not recommended to disable sandboxing as it pollutes the build environment and could possibly cause more build errors. Anything from nixpkgs expects to be built with the sandbox on.

The most common fix is to disable sandboxing in the configuration file:

/etc/nix/nix.conf

# disable sandboxing
sandbox = false

Then restart the nix-daemon.service.

Locale warnings

The Nixos wiki recommends running export LOCALE_ARCHIVE=/usr/lib/locale/locale-archive. Alternatively, export the environment variable LC_ALL=C.