NixOS modules: Difference between revisions

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VisualWikitext

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 <dt><code>modulesPath</code></dt>
-<dd><p>The location of the <code>module</code> directory of NixOS.</p>
+<dd>The location of the <code>module</code> directory of NixOS.</dd>
-<p>Parsed from the first entry in NIX_PATH, for example:<br>
-<code>NIX_PATH=/nix/var/nix/profiles/per-user/root/channels/nixos:nixpkgs=/etc/nixos/nixpkgs:nixos-config=/etc/nixos/configuration.nix</code><br>
-&rarr; <code>modulesPath = /nix/var/nix/profiles/per-user/root/channels/nixos/nixos/modules</code></p>
-<p>note: <code>NIX_PATH</code> is empty when [[Flakes#Using nix flakes with NixOS|Using nix flakes with NixOS]],<br>
-and nix will throw <code>undefined variable 'modulesPath'</code></p>
-</dd>
 </dl>
+==== modulesPath ====
+Some modules use <code>modulesPath</code> to import nixos libraries
+For example <code>nixos/modules/virtualisation/digital-ocean-config.nix</code>
+<pre>
+{ config, pkgs, lib, modulesPath, ... }:
+  imports = [
+    (modulesPath + "/profiles/qemu-guest.nix")
+    (modulesPath + "/virtualisation/digital-ocean-init.nix")
+  ];
+</pre>
+The Nix variable <code>modulesPath</code> is parsed from the environment variable <code>NIX_PATH</code>
+When <code>NIX_PATH</code> is empty, Nix can throw the error <code>undefined variable 'modulesPath'</code>
+<code>NIX_PATH</code> should look something like this:
+<pre>
+echo $NIX_PATH | tr : '\n'
+nixpkgs=/nix/var/nix/profiles/per-user/root/channels/nixos
+nixos-config=/etc/nixos/configuration.nix
+/nix/var/nix/profiles/per-user/root/channels
+</pre>
+Here, the <code>modulesPath</code> is <code>/nix/var/nix/profiles/per-user/root/channels</code>
+When a Nix expression calls <code>import <nixpkgs></code>,<br>
+then Nix will load <code>/nix/var/nix/profiles/per-user/root/channels/nixos</code>
 === Imports ===