iwconfig 显示 wifi 加密狗，但“iw dev”不显示任何内容

Question

该命令iw dev不显示 wifi 加密狗，也没有显示rfkill list ，但是iwconfig：

$ iw dev
$ echo $?
0
$ rfkill list all
1: hci0: Bluetooth
    Soft blocked: no
    Hard blocked: no
$ iwconfig 2>/dev/null
wlx0      unassociated  Nickname:"rtl_wifi"
          Mode:Managed  Access Point: Not-Associated   Sensitivity:0/0  
          Retry:off   RTS thr:off   Fragment thr:off
          Power Management:off
          Link Quality:0  Signal level:0  Noise level:0
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0

如果iwconfig可以“看到”Wi-Fi 加密狗，我认为就不需要重建r8712u驱动程序。

以下是有关此加密狗的更多信息：

$ lsusb -s 1:19 
Bus 001 Device 019: ID 06f8:e031 Guillemot Corp. Hercules HWNUm-300 Wireless N mini [Realtek RTL8191SU]
$ lsusb -t | grep Dev.19
    |__ Port 1: Dev 19, If 0, Class=Vendor Specific Class, Driver=r8712u, 480M
$ inxi -Nxx
Network:   Device-1: Realtek RTL8111/8168/8411 PCI Express Gigabit Ethernet vendor: ASUSTeK P8P67 and other motherboards 
           driver: r8169 v: 2.3LK-NAPI port: e800 bus ID: 03:00.0 chip ID: 10ec:8168 
           Device-2: Guillemot Hercules HWNUm-300 Wireless N mini [Realtek RTL8191SU] type: USB driver: r8712u bus ID: 1-1:19 
           chip ID: 06f8:e031 

wireless-tools 和 iw 包已经安装：

$ dpkg -l wireless-tools iw
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name                     Version           Architecture      Description
+++-========================-=================-=================-======================================================
ii  iw                       3.17-1            amd64             tool for configuring Linux wireless devices
ii  wireless-tools           30~pre9-8ubuntu1  amd64             Tools for manipulating Linux Wireless Extensions

顺便说一下，我正在使用 Ubuntu 16.04.6 LTS :-)