59 lines
2.3 KiB
XML
59 lines
2.3 KiB
XML
<section xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xml:id="sec-ad-hoc-packages">
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<title>Ad-Hoc Package Management</title>
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<para>
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With the command <literal>nix-env</literal>, you can install and
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uninstall packages from the command line. For instance, to install
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Mozilla Thunderbird:
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</para>
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<programlisting>
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$ nix-env -iA nixos.thunderbird
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</programlisting>
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<para>
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If you invoke this as root, the package is installed in the Nix
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profile <literal>/nix/var/nix/profiles/default</literal> and visible
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to all users of the system; otherwise, the package ends up in
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<literal>/nix/var/nix/profiles/per-user/username/profile</literal>
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and is not visible to other users. The <literal>-A</literal> flag
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specifies the package by its attribute name; without it, the package
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is installed by matching against its package name (e.g.
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<literal>thunderbird</literal>). The latter is slower because it
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requires matching against all available Nix packages, and is
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ambiguous if there are multiple matching packages.
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</para>
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<para>
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Packages come from the NixOS channel. You typically upgrade a
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package by updating to the latest version of the NixOS channel:
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</para>
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<programlisting>
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$ nix-channel --update nixos
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</programlisting>
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<para>
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and then running <literal>nix-env -i</literal> again. Other packages
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in the profile are <emphasis>not</emphasis> affected; this is the
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crucial difference with the declarative style of package management,
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where running <literal>nixos-rebuild switch</literal> causes all
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packages to be updated to their current versions in the NixOS
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channel. You can however upgrade all packages for which there is a
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newer version by doing:
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</para>
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<programlisting>
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$ nix-env -u '*'
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</programlisting>
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<para>
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A package can be uninstalled using the <literal>-e</literal> flag:
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</para>
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<programlisting>
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$ nix-env -e thunderbird
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</programlisting>
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<para>
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Finally, you can roll back an undesirable <literal>nix-env</literal>
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action:
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</para>
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<programlisting>
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$ nix-env --rollback
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</programlisting>
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<para>
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<literal>nix-env</literal> has many more flags. For details, see the
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nix-env(1) manpage or the Nix manual.
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</para>
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</section>
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