nixpkgs/nixos/doc/manual/administration/rollback.xml
Jan Tojnar e6ce041cae
nixos/doc: Improve code listings
By adding prompts and replaceables and removing unnecessary indentation.
2020-09-23 01:25:25 +02:00

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<section xmlns="http://docbook.org/ns/docbook"
xmlns:xlink="http://www.w3.org/1999/xlink"
xmlns:xi="http://www.w3.org/2001/XInclude"
version="5.0"
xml:id="sec-rollback">
<title>Rolling Back Configuration Changes</title>
<para>
After running <command>nixos-rebuild</command> to switch to a new
configuration, you may find that the new configuration doesnt work very
well. In that case, there are several ways to return to a previous
configuration.
</para>
<para>
First, the GRUB boot manager allows you to boot into any previous
configuration that hasnt been garbage-collected. These configurations can
be found under the GRUB submenu “NixOS - All configurations”. This is
especially useful if the new configuration fails to boot. After the system
has booted, you can make the selected configuration the default for
subsequent boots:
<screen>
<prompt># </prompt>/run/current-system/bin/switch-to-configuration boot</screen>
</para>
<para>
Second, you can switch to the previous configuration in a running system:
<screen>
<prompt># </prompt>nixos-rebuild switch --rollback</screen>
This is equivalent to running:
<screen>
<prompt># </prompt>/nix/var/nix/profiles/system-<replaceable>N</replaceable>-link/bin/switch-to-configuration switch</screen>
where <replaceable>N</replaceable> is the number of the NixOS system
configuration. To get a list of the available configurations, do:
<screen>
<prompt>$ </prompt>ls -l /nix/var/nix/profiles/system-*-link
<replaceable>...</replaceable>
lrwxrwxrwx 1 root root 78 Aug 12 13:54 /nix/var/nix/profiles/system-268-link -> /nix/store/202b...-nixos-13.07pre4932_5a676e4-4be1055
</screen>
</para>
</section>