Question: I want `Bluetooth` disabled by default. How to do it in elementary os? I've already tried to disable it in settings. But there is no option for this. If I disable it on top bar and login and logout the Bluetooth is enabled.

Answer: 
You can disable it by adding next line to `/etc/rc.local` file with following system restart:

```
rfkill block bluetooth

```
Open `/etc/bluetooth/main.conf` and change `AutoEnable=true` to `AutoEnable=false`.