nixpkgs/nixos/doc/manual/configuration/ad-hoc-packages.xml
2018-05-01 19:57:09 -04:00

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