Barry, Thanks for the help. I will look into it. I fear it may be a bit 'up hill' for me. Can you shed any light as to why: 1) bluetoothctl does not have a command to list the currently connected devices? 2) why btmgmt cannot be run except from the command line? Not even 'btmgmt info' can be run from a script. If it runs, I cannot tell as no output is ever generated and no error is ever listed in the journal. Keith On Wed, Dec 23, 2020 at 1:53 AM Barry Byford <31baz66@xxxxxxxxx> wrote: > > Hello Keith, > > On Wed, 23 Dec 2020 at 00:34, KeithG <ys3al35l@xxxxxxxxx> wrote: > > > > I am developing a RPi based audio player. We are trying to add > > bluetooth capability to this player. We use alsa and not pulse-audio, > > so we need a bit more granular info to get it to run. I have written a > > script which is designed to be triggered by udev when a BT device is > > added or removed. This script will then use bluetoothctl to get the > > capabilities of the device and also add or remove it from a dynamic > > database list of MACs in redis. I have a simple script working as I > > want from the cli. The key command I am using is 'btmgmt con' which is > > the only command I have found that tells me what MACs are currently > > connected. I can run this command from the command line as root. I can > > set the setuid bit of btmgmt and also get it to run as a user (http in > > this case). I cannot, ever, get this command to run when triggered > > from udev. I get no response and no error. > > > > 1) Why is this particular command (query attached BT MACs) not part of > > bluetoothctl? Is there a security issue? > > 2) Why can I not run 'btmgmt con' in a script (bash or php) triggered > > by udev when the device is added or removed? > > 3) is there a 'better way' for me to know what device MAC addresses > > are attached? I have not found another simple way to get this info. > > > > What I am doing in the script is: if an audio source is attached, I > > want to run a bluealsa-aplay service. When an audio sink is attached, > > I want to re-set my audio output to the bluealsa device. If it is not > > an audio device, I do not care, but do keep track of what is attached > > in my database so that the next time the script runs that it is not > > queried and is 'known'. > > > > Thanks for the help. > > > > Keith > > I would suggest that the D-Bus API would be a more appropriate way to > get the information you want. > > The "get managed objects" functionality is a good way to iterate > through all the devices that BlueZ knows about. > There are examples at: > https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/test/bluezutils.py > https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/test/list-devices > > The D-Bus API also allows your code to execute callbacks when a device > is added or its connection state changes. > This is done with the InterfacesAdded and PropertiesChanged signals. > > If you are going to use Python I would suggest the > https://pypi.org/project/pydbus/ library is a more "Pythonic" set of > D-Bus bindings. > > The API is documented at: > https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/doc > > Regards, > Barry
