sudo hciconfig -a
"---------------------------------------"
"HCI Version: 4.2 (0x8) Revision: 0x100"
"---------------------------------------"
| HCI version | Bluetooth version |
|-------------|-------------------|
| 0 (0x0) | 1.0b |
| 1 (0x1) | 1.1 |
| 2 (0x2) | 1.2 |
| 3 (0x3) | 2.0 |
| 4 (0x4) | 2.1 |
| 5 (0x5) | 3.0 |
| 6 (0x6) | 4.0 |
| 7 (0x7) | 4.1 |
| 8 (0x8) | 4.2 |
| 9 (0x9) | 5.0 |
| 10 (0xa) | 5.1 |
| 11 (0xb) | 5.2 |
| 12 (0xc) | 5.3 |