NixOS and Nix functional package manager

Use Cases

Unique package installations, trying out packages, multiple dependencies and version
Multiple versions of packages, complete with dependencies
- Reuse of common package versions
Multiple user support
Reproducible build environments / packages / operating system
- Defined by configuration file
  - Avoid long reinstall and config
- Environments can include only declared packages or merge of declared packages and user’s own environment
- Declared environment setting
- Dockerfiles
- Package files
Roll back easy with generations
Good for reproducibility, stability, frequent system changes

Disadvantages

Requires command line and configuration files

Nix as a Package Manager

How to use NixOS package manager

Examples

Install using Nix shell script

Supports

Atomic upgrades and rollbacks
Nix store, stores packages
Garbage collection
Functional package language
- Nix expressions describe everything that goes into a package build action (a derivation)
Linux and macOS
NixOS is a Linux distribution using Nix for package management and system configuration like /etc files

Usage

Install using quick start instructions

Environment Variables

PATH should include nix binaries
During install, Nix installer will use proxy environment variables

Commands

# List all packages available in installed channels (repositories)
nix-env -qaP

# Install package
nix-env -iA nixpkgs.<package>
 # Test packages with `which <package>`

# uninstall package
nix-env -e <package>

# Build an download dependencies in your Nix store and start bash shell with required environment variables
nix-shell
# Install package and go into shell with it, package only exists in that shell
nix-shell -p <package>
# Nix-shell can use a default `shell.nix` file first and set up a base for other nix-shells in addition to packages specified by `-p`

# --pure` flag makes sure that the bash environment from your system is not inherited, useful for CI environments and reproducible builds/executables
nix-shell --pure

# List installed nix packages
nix-env -q

# `--pure` can be used inside reproducible scripts in shebangs like:
#! /usr/bin/env nix-shell
#! nix-shell --pure -i python -p "python38.withPackages (ps: [ ps.django ])"
#! nix-shell -I nixpkgs=https://github.com/NixOS/nixpkgs/archive/2a601aafdc5605a5133a2ca506a34a3a73377247.tar.gz

import django

print(django)

Upgrade Nix:

Single-user installations of Nix should run this: nix-channel --update; nix-env -iA nixpkgs.nix nixpkgs.cacert

Multi-user Nix users on Linux should run this sudo nix-channel --update; nix-env -iA nixpkgs.nix nixpkgs.cacert; systemctl daemon-reload; systemctl restart nix-daemon

Updates

nix-channel --update nixpkgs - update channels

and

nix-env -u '*' - update packages
Rollbacks

nix-env --rollback - rollback to previous version of packages
Garbage Collection

nix-collect-garbage -d - remove old versions of packages, should be run periodically since other Nix commands do not delete old items

Security

Different user modes are available.

Single user mode = similar to other package management tools, a single user like root does all package management operations, others can use packages, but not do package management
Multiple user mode = every user can do package management operations, software installs do not require root privileges

Appendix - Possible packages for Nixos

VS Code
drawio
openrgb
peazip - not available yet
emacs - available, but not native compilation?
fsearch
microsoft-edge
vlc
keepassxc
firefox-… versions