Nix package manager: Difference between revisions

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Support for declarative configuration in Nix is limited, and the solutions are somewhat fragmented. The only only configuration file officially associated with Nix is <code>nix.conf</code> (usually found in <code>/etc/nix/</code>), which defines a number of settings relating to how Nix, including build, garbage collection, sandboxing, and user permissions. Details on the available options are found in the [https://nixos.org/nix/manual/#sec-conf-file|nix.conf section of the manual]. Since most scenarios involve using [[Nixpkgs]], configuration of <code>~/.config/nixpkgs/config.nix</code> is often also helpful; here package overrides can be specified. Work on Nix user profiles is well underway, see [https://github.com/NixOS/nixpkgs/pull/9250|PR 9250].

=== Imperative Operations ===

==== User Environments ====

Nix offers an imperative package management command line tool - <code>nix-env</code> - which can be used to install packages at the user level. Packages installed using <code>nix-env</code> are only available to the given user, and do not change system state.

{| class="wikitable"

|+ Common <code>nix-env</code> Commands

|-

|Searching for packages

|<code>nix-env -qaP '.*packagename.*'</code>

|-

|Installing a package

|<code>nix-env -i packagename</code>

|-

|List installed packages

|<code>nix-env -q</code>

|-

|Uninstall packages

|<code>nix-env -e packagename</code>

|-

|Upgrade packages

|<code>nix-env -u</code>

|}

==== Channels ====

Nix ''channels'' are mechanisms for distributing Nix expressions as well as the associated binaries for them; a Nix channel corresponds to a repository in a conventional package management system. Official Nix channels are automatically updated once tests are passed in Nixpkgs' [[Hydra]] instance. It is also possible to create one's own Nix channels, but here we focus the official channels. See the NixOS site for [https://nixos.org/channels/ a full list of official channels].

NixOS is distributed through a number of channels. These NixOS channels can be broadly categorised into ''stable'' and ''unstable'' channels, and ''large'' and ''small'' channels:

* Stable/unstable:

** Stable channels (<code>nixos-17.09</code>) provide conservative updates for fixing bugs and security vulnerabilities, but do not receive major updates after initial release. New stable channels are released every six months.

** Unstable channels (<code>nixos-unstable</code>, <code>nixos-unstable-small</code>) correspond to the main development branch of Nixpkgs, delivering the latest tested updates on a rolling basis.

* Large/small:

** Large channels (<code>nixos-17.09</code>, <code>nixos-unstable</code>) provide binary builds for the full breadth of Nixpkgs.

** Small channels (<code>nixos-17.09-small</code>, <code>nixos-unstable-small</code>) are identical to large channels, but contain fewer binaries. This means they update faster, but require more to be built from source.

Most users will want the stable/large channel, currently <code>nixos-17.09</code>.

Like packages installed via <code>nix-env</code>, channels are managed at user-level. The following are the most common commands for Nix channel management:

{| class="wikitable"

|+ Common nix-channel commands

|-

|Listing current channels

|<code>nix-channel --list</code>

|-

| Adding a primary channel

|<code><nowiki>nix-channel --add https://nixos.org/channels/channel-name nixos</nowiki></code>

|-

| Adding other channels

|<code><nowiki>nix-channel --add https://some.channel/url my-alias</nowiki></code>

|-

| Remove a channel

|<code>nix-channel --remove channel-alias</code>

|-

| Updating a channel

|<code>nix-channel --update channel-alias</code>

|-

| Updating all channels

|<code>nix-channel --update</code>

|}

Note that updating channels won't cause a rebuild in itself; if you want to update channels and rebuild, you can run <code>nixos rebuild --upgrade</code> to do both in one step.

== Internals ==

@@ Line 12: / Line 12: @@
 Support for declarative configuration in Nix is limited, and the solutions are somewhat fragmented. The only only configuration file officially associated with Nix is <code>nix.conf</code> (usually found in <code>/etc/nix/</code>), which defines a number of settings relating to how Nix, including build, garbage collection, sandboxing, and user permissions. Details on the available options are found in the [https://nixos.org/nix/manual/#sec-conf-file|nix.conf section of the manual]. Since most scenarios involve using [[Nixpkgs]], configuration of <code>~/.config/nixpkgs/config.nix</code> is often also helpful; here package overrides can be specified. Work on Nix user profiles is well underway, see [https://github.com/NixOS/nixpkgs/pull/9250|PR 9250].
+=== Imperative Operations ===
+====  User Environments ====
+Nix offers an imperative package management command line tool - <code>nix-env</code> - which can be used to install packages at the user level. Packages installed using <code>nix-env</code> are only available to the given user, and do not change system state.
+{|  class="wikitable"
+|+ Common <code>nix-env</code> Commands
+|-
+|Searching for packages
+|<code>nix-env -qaP '.*packagename.*'</code>
+|-
+|Installing a package
+|<code>nix-env -i packagename</code>
+|-
+|List installed packages
+|<code>nix-env -q</code>
+|-
+|Uninstall packages
+|<code>nix-env -e packagename</code>
+|-
+|Upgrade packages
+|<code>nix-env -u</code>
+|}
+==== Channels ====
+Nix ''channels'' are mechanisms for distributing Nix expressions as well as the associated binaries for them; a Nix channel corresponds to a repository in a conventional package management system. Official Nix channels are automatically updated once tests are passed in Nixpkgs' [[Hydra]] instance. It is also possible to create one's own Nix channels, but here we focus the official channels. See the NixOS site for [https://nixos.org/channels/ a full list of official channels].
+NixOS is distributed through a number of channels. These NixOS channels can be broadly categorised into ''stable'' and ''unstable'' channels, and ''large'' and ''small'' channels:
+* Stable/unstable:
+** Stable channels (<code>nixos-17.09</code>) provide conservative updates for fixing bugs and security vulnerabilities, but do not receive major updates after initial release. New stable channels are released every six months.
+** Unstable channels (<code>nixos-unstable</code>, <code>nixos-unstable-small</code>) correspond to the main development branch of Nixpkgs, delivering the latest tested updates on a rolling basis.
+* Large/small:
+** Large channels (<code>nixos-17.09</code>, <code>nixos-unstable</code>) provide binary builds for the full breadth of Nixpkgs.
+** Small channels (<code>nixos-17.09-small</code>, <code>nixos-unstable-small</code>) are identical to large channels, but contain fewer binaries. This means they update faster, but require more to be built from source.
+Most users will want the stable/large channel, currently <code>nixos-17.09</code>.
+Like packages installed via <code>nix-env</code>, channels are managed at user-level. The following are the most common commands for Nix channel management:
+{| class="wikitable"
+|+ Common nix-channel commands
+|-
+|Listing current channels
+|<code>nix-channel --list</code>
+|-
+| Adding a primary channel
+|<code><nowiki>nix-channel --add https://nixos.org/channels/channel-name nixos</nowiki></code>
+|-
+| Adding other channels
+|<code><nowiki>nix-channel --add https://some.channel/url my-alias</nowiki></code>
+|-
+| Remove a channel
+|<code>nix-channel --remove channel-alias</code>
+|-
+| Updating a channel
+|<code>nix-channel --update channel-alias</code>
+|-
+| Updating all channels
+|<code>nix-channel --update</code>
+|}
+Note that updating channels won't cause a rebuild in itself; if you want to update channels and rebuild, you can run <code>nixos rebuild --upgrade</code> to do both in one step.
 == Internals ==