nixpkgs/nixos/doc/manual/configuration/declarative-packages.xml
Jan Tojnar 6b3c3c817a
nixos/doc: suggest checking options for declarative package mgmt
Some programs might not work without systemd services registered or do not work at full capacity without NixOS module.
2020-01-18 02:17:36 +01:00

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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-declarative-package-mgmt">
<title>Declarative Package Management</title>
<para>
With declarative package management, you specify which packages you want on
your system by setting the option
<xref linkend="opt-environment.systemPackages"/>. For instance, adding the
following line to <filename>configuration.nix</filename> enables the Mozilla
Thunderbird email application:
<programlisting>
<xref linkend="opt-environment.systemPackages"/> = [ pkgs.thunderbird ];
</programlisting>
The effect of this specification is that the Thunderbird package from Nixpkgs
will be built or downloaded as part of the system when you run
<command>nixos-rebuild switch</command>.
</para>
<note>
<para>
Some packages require additional global configuration such as D-Bus or systemd service registration so adding them to <xref linkend="opt-environment.systemPackages"/> might not be sufficient. You are advised to check the <link xlink:href="#ch-options">list of options</link> whether a NixOS module for the package does not exist.
</para>
</note>
<para>
You can get a list of the available packages as follows:
<screen>
<prompt>$ </prompt>nix-env -qaP '*' --description
nixos.firefox firefox-23.0 Mozilla Firefox - the browser, reloaded
<replaceable>...</replaceable>
</screen>
The first column in the output is the <emphasis>attribute name</emphasis>,
such as <literal>nixos.thunderbird</literal>.
</para>
<para>
Note: the <literal>nixos</literal> prefix tells us that we want to get the
package from the <literal>nixos</literal> channel and works only in CLI tools.
In declarative configuration use <literal>pkgs</literal> prefix (variable).
</para>
<para>
To “uninstall” a package, simply remove it from
<xref linkend="opt-environment.systemPackages"/> and run
<command>nixos-rebuild switch</command>.
</para>
<xi:include href="customizing-packages.xml" />
<xi:include href="adding-custom-packages.xml" />
</section>