2020-04-24 23:36:52 +00:00
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<section xmlns="http://docbook.org/ns/docbook"
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xmlns:xlink="http://www.w3.org/1999/xlink"
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xmlns:xi="http://www.w3.org/2001/XInclude"
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version="5.0"
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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 <command>nixos-rebuild</command> to switch to a new
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configuration, you may find that the new configuration doesn’t work very
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well. In that case, there are several ways to return to a previous
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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 configurations can
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be found under the GRUB submenu “NixOS - All configurations”. This is
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especially useful if the new configuration fails to boot. After the system
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has booted, you can make the selected configuration the default for
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subsequent boots:
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<screen>
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2020-09-25 04:45:31 +00:00
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<prompt># </prompt>/run/current-system/bin/switch-to-configuration boot</screen>
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2020-04-24 23:36:52 +00:00
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</para>
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<para>
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Second, you can switch to the previous configuration in a running system:
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<screen>
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2020-09-25 04:45:31 +00:00
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<prompt># </prompt>nixos-rebuild switch --rollback</screen>
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2020-04-24 23:36:52 +00:00
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This is equivalent to running:
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<screen>
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2020-09-25 04:45:31 +00:00
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<prompt># </prompt>/nix/var/nix/profiles/system-<replaceable>N</replaceable>-link/bin/switch-to-configuration switch</screen>
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2020-04-24 23:36:52 +00:00
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where <replaceable>N</replaceable> 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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<screen>
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<prompt>$ </prompt>ls -l /nix/var/nix/profiles/system-*-link
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<replaceable>...</replaceable>
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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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</screen>
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</para>
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</section>
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