user60561's questions

我有一个 USB Zigbee 加密狗，但无法连接到它。它短暂地出现在 中/dev/ttyUSB0，但很快就消失了。我在控制台中看到以下输出：

$ dmesg --follow
...
[  738.365561] usb 1-10: new full-speed USB device number 8 using xhci_hcd
[  738.607730] usb 1-10: New USB device found, idVendor=1a86, idProduct=7523, bcdDevice= 2.64
[  738.607737] usb 1-10: New USB device strings: Mfr=0, Product=2, SerialNumber=0
[  738.607739] usb 1-10: Product: USB Serial
[  738.619446] ch341 1-10:1.0: ch341-uart converter detected
[  738.633501] usb 1-10: ch341-uart converter now attached to ttyUSB0
[  738.732348] audit: type=1130 audit(1632606446.974:2212): pid=1 uid=0 auid=4294967295 ses=4294967295 msg='unit=brltty-device@sys-devices-pci0000:00-0000:00:01.3-0000:03:00.0-usb1-1\x2d10 comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'
[  738.768081] audit: type=1130 audit(1632606447.007:2213): pid=1 uid=0 auid=4294967295 ses=4294967295 msg='unit=brltty@-sys-devices-pci0000:00-0000:00:01.3-0000:03:00.0-usb1-1\x2d10 comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'
[  738.776433] usb 1-10: usbfs: interface 0 claimed by ch341 while 'brltty' sets config #1
[  738.783508] ch341-uart ttyUSB0: ch341-uart converter now disconnected from ttyUSB0
[  738.783521] ch341 1-10:1.0: device disconnected
[  739.955783] input: BRLTTY 6.4 Linux Screen Driver Keyboard as /devices/virtual/input/input35
...

我有以下命令：

sudo docker logs -f <id> | awk '/Listening on / {print $3; exit 0;}'

据我了解，awk 应该找到与模式匹配的第一行，打印正确的列，然后退出。然而，这并不总是发生：大多数时候它只是打印正确的列并挂起，尽管偶尔它会正确退出。

我试过了

$ sudo stdbuf -i0 -o0 -e0 docker logs ...  # hangs
$ sudo docker logs ... | cat | awk ... # hangs

在尝试制作一个最小的示例时，我还尝试使用mkfifo, 和 using制作管道，cat foo | awk ...但这并没有挂起。

的输出docker logs -f <id>是

Listening on 172.17.0.2/16
...

然后它保持打开状态，但不写任何其他内容。

我不明白发生了什么 - 有没有人有任何想法？