sudo journalctl -f | grep bluetooth* hci_usb zephyr master

sudo journalctl -f | grep bluetooth*
Oct 18 02:35:25 ubuntu bluetoothd[704]: src/agent.c:agent_disconnect() Agent :1.158 disconnected
Oct 18 02:35:25 ubuntu bluetoothd[704]: src/agent.c:agent_destroy() agent :1.158
Oct 18 02:35:25 ubuntu bluetoothd[704]: src/agent.c:agent_unref() 0x55b1b2db0420: ref=0
Oct 18 02:36:16 ubuntu bluetoothd[704]: src/rfkill.c:rfkill_event() RFKILL event idx 5 type 2 op 0 soft 0 hard 0