Cheatsheet
A cheat sheet and rough mapping between Ubuntu and NixOS
This is meant to give you basic ideas and get you unstuck. NixOS being very different from most distributions, a deeper understanding will be necessary sooner or later! Follow the links to the manual pages and browse the wiki to find real NixOS tutorials.
The system-wide column is the equivalent of using apt under Ubuntu.
TODO Provide well-commented sample configuration.nix and ~/.nixpkgs/config.nix files with examples of common tasks.
| Task | Ubuntu | NixOS (system-wide and root) | NixOS (user) and Nix in general | |
|---|---|---|---|---|
| Basic concepts | ||||
| This column will let you do everything you can with Ubuntu and more. | This column just isn't possible in Ubuntu. | |||
| Who can install packages and who can run them? | All packages are always system-wide and only root can install packages. | Packages root installs are system-wide. It does so through through /etc/nixos/configuration.nix. If root installs packages the same way users do, through ~/.nixpkgs/config.nix, they are also global. Root's default profile is the system-wide default profile. | Users can install their own packages and have their own profiles (environments) through ~/.nixpkgs/config.nix | |
| Package manager | apt which is really running on top of dpkg, sometimes wrapped by UIs like aptitude. | nix, but many system-wide operations are provided by nixos packages. | Just nix without the involvement of nixos. | |
| How do you select your official sources and major releases | These are baked into the distribution (e.g. Ubuntu version X). Upgrades are hard and permanent. | At any time you select from a collection of channels. They're system-wide when set by root. You can roll back changes or switch channels with ease. | Channels are per-user if they're not set by root. | |
| Where are packages installed? | apt installs globally into /bin/, /usr/, etc. | System-wide packages are in /run/current-system/sw/ (these are installed because of /etc/nixos/configuration.nix) and /nix/var/nix/profiles/default/bin/ (this is the profile managed by root). Note that the files are just symlinks to the real packages managed by nix /nix/store/. | User packages are in ~/.nix-profile/. Note that the files are just symlinks to the real packages managed by nix in /nix/store/. | |
| When changes take effect | As soon as the command runs. Commands are not atomic and can leave your machine in a bad state. | Most of the time you modify the configuration file and apply changes with nixos-rebuild switch
TODO How does one get nixos to do all the work for a switch and separate out the actual switching from fetching/building? |
Most of the time you apply changes with nix-env -i all
TODO How does one get nix to do all the work for a switch and separate out the actual switching from fetching/building? | |
| Packages | Uniformly referred to as packages | Technically called "derivations" but everyone calls them packages. | Technically called "derivations" but everyone calls them packages. | |
| Package management | ||||
| Install a package | sudo apt-get install emacs |
In /etc/nixos/configuration.nix:
If it's a program add to systemPackages: systemPackages = with pkgs;
[ <other packages...> emacs ];
If it's a service add: services.openssh.enable = true; |
nix-env -i emacs Or with collections, add the package to your ~/.nixpkgs/config.nix and run nix-env -i all | |
| Uninstall a package | sudo apt-get remove emacs |
remove from /etc/nixos/configuration.nix
sudo nixos-rebuild switch |
||
| Uninstall a package removing its configuration | apt-get purge emacs |
All configuration is in configuration.nix | ||
| Update the list of packages | sudo apt-get update |
sudo nix-channel --update |
nix-channel --update | |
| Upgrade packages | sudo apt-get upgrade |
sudo nixos-rebuild switch |
nix-env -u | |
| Check for broken dependencies | sudo apt-get check |
nix-store --verify --check-contents |
unneeded! | |
| List package dependencies | apt-cache depends emacs |
nix-store --query --requisites $(readlink -f /run/current-system) nix-store -q --tree /nix/var/nix/profiles/system |
nix-store --query --references\ $(nix-instantiate '<nixpkgs>' -A emacs) For installed packages: nix-store --query --references $(which emacs) | |
| List which packages depend on this one (reverse dependencies) | apt-cache rdepends emacs |
For installed packages (only print reverse dependencies *which are already installed*):
nix-store --query --referrers $(which emacs) | ||
| Verify all installed packages | debsums |
sudo nix-store --verify --check-contents |
nix-store --verify --check-contents | |
| Fix packages with failed checksums | Reinstall broken packages | sudo nix-store --verify --check-contents --repair |
nix-store --verify --check-contents --repair | |
| Select major version and stable/unstable | Change sources.list and apt-get dist-upgrade. A an extremely infrequent and destructive operation. The nix variants are safe and easy to use. | nix-channel --add\ https://nixos.org/channels/nixpkgs-unstable <name> Add the unstable channel. At that address you will find names for other versions and variants. Name can be any string. nix-channel --remove <name> To eliminate a channel. nix-channel --list To show all installed channel. |
When run by a user channels work locally, when run by root they're used as the system-wide channels. | |
| Private package repository | PPA | Define your package tree as in the general column, and include it in configuration.nix, then list your packages in systemPackages to make them available system wide | See [1] | |
| Install a particular version of a package | ||||
| Package configuration | ||||
| Configure a package | sudo dpkg-reconfigure <package> |
edit /etc/nixos/configuration.nix | edit ~/.nixpkgs/config.nix TODO More details about how to edit | |
| List package options | ||||
| Global package configuration | Modify configuration file in /etc/ | |||
| Package configuration | ||||
| Find packages | apt-cache search emacs |
nix-env -qaP '.*emacs.*' |
nix-env -qaP '.*emacs.*' | |
| Show package description | apt-cache show emacs |
nix-env -qa --description '.*emacs.*' |
nix-env -qa --description '.*emacs.*' | |
| Show files installed by package | dpkg -L emacs |
readlink -f $(which emacs) /nix/store/ji06y4haijly0i0knmr986l2dajffv1p-emacs-24.4/bin/emacs-24.4 then du -a /nix/store/ji06y4haijly0i0knmr986l2dajffv1p-emacs-24.4 |
||
| Show package for file | dpkg -S /usr/bin/emacs |
follow the symlink | follow the symlink | |
| Services | ||||
| Start a service | sudo service apache start |
sudo systemctl start apache |
||
| Stop a service | sudo service apache stop |
sudo systemctl stop apache |
||
| Where your log files live | /var/log/ | System-wide packages /var/log/ | User packages ~/.nix-profile/var/log/ | |
| Adding a user | sudo adduser alice | Add users.extraUsers.alice =
{ isNormalUser = true;
home = "/home/alice";
description = "Alice Foobar";
extraGroups = [ "wheel" "networkmanager" ];
openssh.authorizedKeys.keys =
[ "ssh-dss AAAAB3Nza... alice@foobar" ];
}; to to /etc/nixos/configuration.nix and then call nixos-rebuild switch |
||
| Misc tasks | ||||
| List binaries | ls /usr/bin/ |
ls /run/current-system/sw/bin &&\ ls /nix/var/nix/profiles/default/bin/ |
ls ~/.nix-profile/bin | |
| Get the current version number | cat /etc/debian_version |
nixos-version |
nixos-version | |
| Get sources for a package | apt-get source emacs |
In Debian, apt-get source gets both the patched upstream source and the recipe for the package. Those need two steps in Nix.
To find the package recipe: grep -r emacs $(nix-instantiate --eval --expr '<nixpkgs>')To download the source as specified by the package recipe: nix-build '<nixpkgs>' -A emacs.srcThe patched source is usually not a derivation itself, but can be produced for most packages with the following command: nix-shell '<nixpkgs>' -A emacs\ --command 'unpackPhase; patchPhase' | ||
| Compile & install a package from source | git clone foobar
cat >default.nix <<EOF
with import <nixpkgs> { };
stdenv.lib.overrideDerivation foobar (oldAttrs : {
src = ./foobar;
})
EOF
nix-build
| |||
| Install a binary package | ||||
| Install a .deb | dpkg -i package.deb |
Install dpkg with Nix, then dpkg -i package.deb | ||