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1<section xmlns="http://docbook.org/ns/docbook"
2 xmlns:xlink="http://www.w3.org/1999/xlink"
3 xmlns:xi="http://www.w3.org/2001/XInclude"
4 version="5.0"
5 xml:id="sec-custom-packages">
6
7<title>Adding Custom Packages</title>
8
9<para>It’s possible that a package you need is not available in NixOS.
10In that case, you can do two things. First, you can clone the Nixpkgs
11repository, add the package to your clone, and (optionally) submit a
12patch or pull request to have it accepted into the main Nixpkgs
13repository. This is described in detail in the <link
14xlink:href="http://nixos.org/nixpkgs/manual">Nixpkgs manual</link>.
15In short, you clone Nixpkgs:
16
17<screen>
18$ git clone git://github.com/NixOS/nixpkgs.git
19$ cd nixpkgs
20</screen>
21
22Then you write and test the package as described in the Nixpkgs
23manual. Finally, you add it to
24<literal>environment.systemPackages</literal>, e.g.
25
26<programlisting>
27environment.systemPackages = [ pkgs.my-package ];
28</programlisting>
29
30and you run <command>nixos-rebuild</command>, specifying your own
31Nixpkgs tree:
32
33<screen>
34# nixos-rebuild switch -I nixpkgs=/path/to/my/nixpkgs</screen>
35
36</para>
37
38<para>The second possibility is to add the package outside of the
39Nixpkgs tree. For instance, here is how you specify a build of the
40<link xlink:href="http://www.gnu.org/software/hello/">GNU Hello</link>
41package directly in <filename>configuration.nix</filename>:
42
43<programlisting>
44environment.systemPackages =
45 let
46 my-hello = with pkgs; stdenv.mkDerivation rec {
47 name = "hello-2.8";
48 src = fetchurl {
49 url = "mirror://gnu/hello/${name}.tar.gz";
50 sha256 = "0wqd8sjmxfskrflaxywc7gqw7sfawrfvdxd9skxawzfgyy0pzdz6";
51 };
52 };
53 in
54 [ my-hello ];
55</programlisting>
56
57Of course, you can also move the definition of
58<literal>my-hello</literal> into a separate Nix expression, e.g.
59<programlisting>
60environment.systemPackages = [ (import ./my-hello.nix) ];
61</programlisting>
62where <filename>my-hello.nix</filename> contains:
63<programlisting>
64with import <nixpkgs> {}; # bring all of Nixpkgs into scope
65
66stdenv.mkDerivation rec {
67 name = "hello-2.8";
68 src = fetchurl {
69 url = "mirror://gnu/hello/${name}.tar.gz";
70 sha256 = "0wqd8sjmxfskrflaxywc7gqw7sfawrfvdxd9skxawzfgyy0pzdz6";
71 };
72}
73</programlisting>
74
75This allows testing the package easily:
76<screen>
77$ nix-build my-hello.nix
78$ ./result/bin/hello
79Hello, world!
80</screen>
81
82</para>
83
84</section>