You can also the [`rfkill`][1] command to disable or enable the Wi-Fi interface(s). This is how the interface is disabled by Raspbian with a new installation before the country has been configured in the Wi-Fi settings (e.g using `raspi-config`). You can disable the Wi-Fi interface(s):

 sudo rfkill block wifi

Enable it like this:

 sudo rfkill unblock wifi

And check the current state of the interfaces:

 rfkill list

If you want enable/disable specific interfaces use the index shown by `rfkill list` to the un/block command.

The rfkill state will be maintained across reboots as it is reinstated on bootup by systemd.


 [1]: https://wireless.wiki.kernel.org/en/users/Documentation/rfkill