pyrox.dev
1<section xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xml:id="sec-rollback">
2 <title>Rolling Back Configuration Changes</title>
3 <para>
4 After running <literal>nixos-rebuild</literal> to switch to a new
5 configuration, you may find that the new configuration doesn’t work
6 very well. In that case, there are several ways to return to a
7 previous configuration.
8 </para>
9 <para>
10 First, the GRUB boot manager allows you to boot into any previous
11 configuration that hasn’t been garbage-collected. These
12 configurations can be found under the GRUB submenu <quote>NixOS -
13 All configurations</quote>. This is especially useful if the new
14 configuration fails to boot. After the system has booted, you can
15 make the selected configuration the default for subsequent boots:
16 </para>
17 <programlisting>
18# /run/current-system/bin/switch-to-configuration boot
19</programlisting>
20 <para>
21 Second, you can switch to the previous configuration in a running
22 system:
23 </para>
24 <programlisting>
25# nixos-rebuild switch --rollback
26</programlisting>
27 <para>
28 This is equivalent to running:
29 </para>
30 <programlisting>
31# /nix/var/nix/profiles/system-N-link/bin/switch-to-configuration switch
32</programlisting>
33 <para>
34 where <literal>N</literal> is the number of the NixOS system
35 configuration. To get a list of the available configurations, do:
36 </para>
37 <programlisting>
38$ ls -l /nix/var/nix/profiles/system-*-link
39...
40lrwxrwxrwx 1 root root 78 Aug 12 13:54 /nix/var/nix/profiles/system-268-link -> /nix/store/202b...-nixos-13.07pre4932_5a676e4-4be1055
41</programlisting>
42</section>