42 lines
1.6 KiB
XML
42 lines
1.6 KiB
XML
<section xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xml:id="sec-rollback">
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<title>Rolling Back Configuration Changes</title>
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<para>
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After running <literal>nixos-rebuild</literal> to switch to a new
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configuration, you may find that the new configuration doesn’t work
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very well. In that case, there are several ways to return to a
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previous configuration.
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</para>
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<para>
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First, the GRUB boot manager allows you to boot into any previous
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configuration that hasn’t been garbage-collected. These
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configurations can be found under the GRUB submenu <quote>NixOS -
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All configurations</quote>. This is especially useful if the new
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configuration fails to boot. After the system has booted, you can
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make the selected configuration the default for subsequent boots:
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</para>
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<programlisting>
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# /run/current-system/bin/switch-to-configuration boot
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</programlisting>
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<para>
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Second, you can switch to the previous configuration in a running
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system:
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</para>
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<programlisting>
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# nixos-rebuild switch --rollback
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</programlisting>
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<para>
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This is equivalent to running:
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</para>
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<programlisting>
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# /nix/var/nix/profiles/system-N-link/bin/switch-to-configuration switch
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</programlisting>
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<para>
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where <literal>N</literal> is the number of the NixOS system
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configuration. To get a list of the available configurations, do:
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</para>
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<programlisting>
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$ ls -l /nix/var/nix/profiles/system-*-link
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...
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lrwxrwxrwx 1 root root 78 Aug 12 13:54 /nix/var/nix/profiles/system-268-link -> /nix/store/202b...-nixos-13.07pre4932_5a676e4-4be1055
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</programlisting>
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</section>
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