which commands are executed by the "bluetooth enable" button?
There are two buttons for triggering Bluetooth availability by a mouse 
click, and they appear to do some magic. I would need to find out about 
this, I am searching for the commands which become executed by these 
buttons.
After a reboot Bluetooth is still deactivated, and for activating it I 
can go here:
System Settings - Network - Bluetooth
There, I find emphasized by alarming color "Bluetooth is disabled" and 
next to it is then nicely provided an "Enable" button which perfectly 
works. After Bluetooth becomes activated in this way, then there appears 
the related System Tray icon in the panel of KDE Plasma, and from now on 
I can there deactivate Bluetooth, or activate it there again, forth and 
back, repeatedly, which works as expected.
In another thread I asked how to set a keyboard shortcut for this 
activation/deactivation of Bluetooth, and quickly got the very helpful 
answer how to set the needed "custom shortcut" (Thanks, Helge!). 
However, the command which has to become executed by the shortcut 
troubles. It worked for Helge, but not for me, and the Internet is full 
about the problem and error message as I receive it.
There obviously is something more going on behind this buttons, than 
simply calling the commands "bluetoothctl power on" or "bluetoothctl 
power off".
I tested the "bluetoothctl" command interactively on a CLI as the user 
or with sudo and got with sub-command "devices" (and others) the error 
message: "No default controller available".
The internet is full of questions about this and by now I could not find 
any good answer. There are suggestions that the problem would have been 
solved after a cold start (not simply a reboot), after driver 
re-installation, booting into Windows and back into Linux, and many more 
weird solutions.
BUT: if I use the mouse in order to trigger the button, then bluetooth 
becomes enabled or disabled without any problems, forth and back, 
repeatedly. And if it first becomes enabled by the mouse click on the 
button, I then afterwards also succeed on the CLI with the commands 
given as a normal user "bluetoothctl power off" and "bluetoothctl power 
on", forth and back, repeatedly (and also the keyboard shortcut works 
for me, then).
Once I use the mouse for deactivating Bluetooth by the button, then the 
bluetoothctl commands again fail with said error message.
Obviously, the buttons know the magic trick how to activate/deactivate 
the communication with the present hardware at a state, when 
bluetoothctl cannot succeed to get access to the device.
I should add, that "systemctl status bluetooth" confirms this service to 
all the time being active, and obviously there are no drivers or 
configurations missing - the buttons can do the job. So, nothing is 
missing but to find out which commands these buttons trigger.
Well, I am now searching for this full series of commands, for achieving 
on the CLI the same result as these buttons are doing it.
Could you help?
Marco.
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