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+<section xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xml:id="sec-replace-modules">
+  <title>Replace Modules</title>
+  <para>
+    Modules that are imported can also be disabled. The option
+    declarations, config implementation and the imports of a disabled
+    module will be ignored, allowing another to take it's place. This
+    can be used to import a set of modules from another channel while
+    keeping the rest of the system on a stable release.
+  </para>
+  <para>
+    <literal>disabledModules</literal> is a top level attribute like
+    <literal>imports</literal>, <literal>options</literal> and
+    <literal>config</literal>. It contains a list of modules that will
+    be disabled. This can either be the full path to the module or a
+    string with the filename relative to the modules path (eg.
+    &lt;nixpkgs/nixos/modules&gt; for nixos).
+  </para>
+  <para>
+    This example will replace the existing postgresql module with the
+    version defined in the nixos-unstable channel while keeping the rest
+    of the modules and packages from the original nixos channel. This
+    only overrides the module definition, this won't use postgresql from
+    nixos-unstable unless explicitly configured to do so.
+  </para>
+  <programlisting language="bash">
+{ config, lib, pkgs, ... }:
+
+{
+  disabledModules = [ &quot;services/databases/postgresql.nix&quot; ];
+
+  imports =
+    [ # Use postgresql service from nixos-unstable channel.
+      # sudo nix-channel --add https://nixos.org/channels/nixos-unstable nixos-unstable
+      &lt;nixos-unstable/nixos/modules/services/databases/postgresql.nix&gt;
+    ];
+
+  services.postgresql.enable = true;
+}
+</programlisting>
+  <para>
+    This example shows how to define a custom module as a replacement
+    for an existing module. Importing this module will disable the
+    original module without having to know it's implementation details.
+  </para>
+  <programlisting language="bash">
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.programs.man;
+in
+
+{
+  disabledModules = [ &quot;services/programs/man.nix&quot; ];
+
+  options = {
+    programs.man.enable = mkOption {
+      type = types.bool;
+      default = true;
+      description = &quot;Whether to enable manual pages.&quot;;
+    };
+  };
+
+  config = mkIf cfg.enabled {
+    warnings = [ &quot;disabled manpages for production deployments.&quot; ];
+  };
+}
+</programlisting>
+</section>