我的问题和解决方案（看似）非常简单：在我的 Kubuntu 19.04 安装上一切都运行良好，然后我安装/卸载了一些东西（主要与 MariaDB 和 Skype 密码存储问题有关，这导致我删除了 AppArmor、密钥环和其他我甚至不明白的东西），现在我的 USB WiFi 不再被检测到了。
我本来不会在这里发帖，但我无论如何也想不出我删除的那个原始包是什么。有没有办法安装/激活 USB WiFi 的默认包/模块？
== 编辑：根据评论中的要求添加诊断信息 ===
root@bandook:~# nmcli device
DEVICE TYPE STATE CONNECTION
wlp6s0 wifi connected Bhokali
enp7s0 ethernet unavailable --
docker0 bridge unmanaged --
lo loopback unmanaged --
root@bandook:~# lshw -C network | grep -i "Wireless interface" -A12 -B1
*-network
description: Wireless interface
product: BCM43142 802.11b/g/n
vendor: Broadcom Inc. and subsidiaries
physical id: 0
bus info: pci@0000:06:00.0
logical name: wlp6s0
version: 01
serial: 9c:d2:1e:e5:47:33
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
configuration: broadcast=yes driver=wl0 driverversion=6.30.223.271 (r587334) ip=192.168.1.7 latency=0 multicast=yes wireless=IEEE 802.11
resources: irq:18 memory:f7900000-f7907fff
root@bandook:~# lspci -knn | grep -A4 -i "Network controller"
06:00.0 Network controller [0280]: Broadcom Inc. and subsidiaries BCM43142 802.11b/g/n [14e4:4365] (rev 01)
Subsystem: Dell Wireless 1704 802.11n + BT 4.0 [1028:0016]
Kernel driver in use: wl
Kernel modules: bcma, wl
07:00.0 Ethernet controller [0200]: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller [10ec:8168] (rev 0c)
root@bandook:~# cat /var/lib/NetworkManager/NetworkManager.state
[main]
NetworkingEnabled=true
WirelessEnabled=true
WWANEnabled=true
root@bandook:~# networkctl status
WARNING: systemd-networkd is not running, output will be incomplete.
● State: n/a
Address: 192.168.1.7 on wlp6s0
172.17.0.1 on docker0
fe80::7ebf:af75:5b36:6c94 on wlp6s0
Gateway: 192.168.1.1 (Binatone Telecommunication Pvt. Ltd) on wlp6s0
fe80::ed2:b5ff:fe82:9fab (Binatone Telecommunication Pvt. Ltd) on wlp6s0
root@bandook:~# lsusb
Bus 001 Device 029: ID 0a5c:21d7 Broadcom Corp. BCM43142 Bluetooth 4.0
Bus 001 Device 004: ID 0bda:5756 Realtek Semiconductor Corp.
Bus 001 Device 024: ID 046d:c52b Logitech, Inc. Unifying Receiver
Bus 001 Device 002: ID 8087:8000 Intel Corp.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 003 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
root@bandook:~# rfkill
ID TYPE DEVICE SOFT HARD
0 wlan phy0 unblocked unblocked
1 wlan brcmwl-0 unblocked unblocked
4 bluetooth hci0 unblocked unblocked