mirror of
https://github.com/NixOS/nixpkgs.git
synced 2024-11-30 01:20:40 +00:00
91 lines
2.7 KiB
XML
91 lines
2.7 KiB
XML
<chapter xmlns="http://docbook.org/ns/docbook"
|
||
xmlns:xlink="http://www.w3.org/1999/xlink"
|
||
version="5.0"
|
||
xml:id="sec-changing-config">
|
||
|
||
<title>Changing the Configuration</title>
|
||
|
||
<para>The file <filename>/etc/nixos/configuration.nix</filename>
|
||
contains the current configuration of your machine. Whenever you’ve
|
||
changed something to that file, you should do
|
||
|
||
<screen>
|
||
$ nixos-rebuild switch</screen>
|
||
|
||
to build the new configuration, make it the default configuration for
|
||
booting, and try to realise the configuration in the running system
|
||
(e.g., by restarting system services).</para>
|
||
|
||
<warning><para>These commands must be executed as root, so you should
|
||
either run them from a root shell or by prefixing them with
|
||
<literal>sudo -i</literal>.</para></warning>
|
||
|
||
<para>You can also do
|
||
|
||
<screen>
|
||
$ nixos-rebuild test</screen>
|
||
|
||
to build the configuration and switch the running system to it, but
|
||
without making it the boot default. So if (say) the configuration
|
||
locks up your machine, you can just reboot to get back to a working
|
||
configuration.</para>
|
||
|
||
<para>There is also
|
||
|
||
<screen>
|
||
$ nixos-rebuild boot</screen>
|
||
|
||
to build the configuration and make it the boot default, but not
|
||
switch to it now (so it will only take effect after the next
|
||
reboot).</para>
|
||
|
||
<para>You can make your configuration show up in a different submenu
|
||
of the GRUB 2 boot screen by giving it a different <emphasis>profile
|
||
name</emphasis>, e.g.
|
||
|
||
<screen>
|
||
$ nixos-rebuild switch -p test </screen>
|
||
|
||
which causes the new configuration (and previous ones created using
|
||
<literal>-p test</literal>) to show up in the GRUB submenu “NixOS -
|
||
Profile 'test'”. This can be useful to separate test configurations
|
||
from “stable” configurations.</para>
|
||
|
||
<para>Finally, you can do
|
||
|
||
<screen>
|
||
$ nixos-rebuild build</screen>
|
||
|
||
to build the configuration but nothing more. This is useful to see
|
||
whether everything compiles cleanly.</para>
|
||
|
||
<para>If you have a machine that supports hardware virtualisation, you
|
||
can also test the new configuration in a sandbox by building and
|
||
running a QEMU <emphasis>virtual machine</emphasis> that contains the
|
||
desired configuration. Just do
|
||
|
||
<screen>
|
||
$ nixos-rebuild build-vm
|
||
$ ./result/bin/run-*-vm
|
||
</screen>
|
||
|
||
The VM does not have any data from your host system, so your existing
|
||
user accounts and home directories will not be available. You can
|
||
forward ports on the host to the guest. For instance, the following
|
||
will forward host port 2222 to guest port 22 (SSH):
|
||
|
||
<screen>
|
||
$ QEMU_NET_OPTS="hostfwd=tcp::2222-:22" ./result/bin/run-*-vm
|
||
</screen>
|
||
|
||
allowing you to log in via SSH (assuming you have set the appropriate
|
||
passwords or SSH authorized keys):
|
||
|
||
<screen>
|
||
$ ssh -p 2222 localhost
|
||
</screen>
|
||
|
||
</para>
|
||
|
||
</chapter>
|