Nix

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

Installation

There are three choices for a Nix installation, one is supported by Arch Linux, the next officially supported by Nix, and the last not being supported at all.

Native

Install the nix package.

Upstream installation script

Download the file with curl --proto '=https' --tlsv1.2 -sSfL https://nixos.org/nix/install -o nix-install.sh, view it: less ./nix-install.sh, and run the script ./nix-install.sh --daemon to start Nix installation.

Warning: Running curl some-url | sh, as the Nix documentation suggests, is considered as a security risk, because it executes unknown code, that might even be corrupted during the download. Therefore it is recommended to manually download the script and check it, before executing it.

archlinux-nix

archlinux-nix^AUR can be used to 'bootstrap' an Arch Linux compatible Nix system by setting up the required groups and permissions.

After installing nix and archlinux-nix^AUR, list the available commands:

$ archlinux-nix

To complete the installation, follow all of these steps:

Prepare Arch for the Nix installation:

# archlinux-nix setup-build-group  # setup build groups
# archlinux-nix bootstrap          # bootstrap the system

Configure a default Nix channel and update it:

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

After first install, and before rebooting, activate Nix in each new shell:

$ source /etc/profile.d/nix{,-daemon}.sh

This makes Nix's daemon (and package manager) functional without rebooting. It updates your PATH to Nix's liking. Check it by echo $PATH. Run this in each new shell session until you have restarted.

Configuration

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

Add required users to the group in order to access the daemon socket.

Add a channel and update it.

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

Tips and tricks

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

If you installed Nix from the official repositories, you must add the directory to your PATH manually.

$ nix-env -iA nixpkgs.hello

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

$ nix-env --uninstall hello

Or you can check the list of installed program by (q stands for query)

$ nix-env -q

You can also check generations by

$ nix-env --list-generations

Check more details in the nix-env(1) manual.

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

Troubleshooting

Permission denied

Running or as user produces

cannot connect to daemon at '/nix/var/nix/daemon-socket/socket: permission denied

If you just installed nix, you need to reboot.

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

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

If the above message shows up when using Nix, the root user will need to update their channels.

# nix-channel --update

Stale sandbox paths

error: while setting up the build environment: executing '/usr/bin/bash': No such file or directory
error: builder for '/nix/store/mh8hl6c7gyyqrnzrln4j2jxg79n32slf-nixpkgs-21.11pre300283.f930ea227ce.drv' failed with exit code 1
error: build of '/nix/store/mh8hl6c7gyyqrnzrln4j2jxg79n32slf-nixpkgs-21.11pre300283.f930ea227ce.drv' failed
error: program '/usr/bin/nix-env' failed with exit code 100

If migrating from archlinux-nix^AUR to nix, make sure to clear out from as there might be stale paths that have been garbage-collected already.

Broken coreutils

There is currently a problem with the provided by the nix package where the busybox provided coreutils override the build environment. One workaround is to install the busybox

# nix-build 'channel:nixpkgs-unstable' -A busybox-sandbox-shell --out-link /opt/busybox-nix

and update the nix configuration to use it

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, then Restart the service.

Nix