我做了什么：
通过 HDMI 连接显示器。的输出
xrandr符合预期：Screen 0: minimum 8 x 8, current 3840 x 1080, maximum 32767 x 32767 eDP1 connected primary 1920x1080+1920+0 (normal left inverted right x axis y axis) 310mm x 170mm 1920x1080 60.01*+ 1400x1050 59.98 1600x900 60.00 1280x1024 60.02 1280x960 60.00 1368x768 60.00 1280x720 60.00 1024x768 60.00 1024x576 60.00 960x540 60.00 800x600 60.32 56.25 864x486 60.00 640x480 59.94 720x405 60.00 640x360 60.00 DP1 disconnected (normal left inverted right x axis y axis) DP2 disconnected (normal left inverted right x axis y axis) HDMI1 disconnected (normal left inverted right x axis y axis) HDMI2 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 530mm x 300mm 1920x1080 60.00*+ 50.00 59.94 1680x1050 59.88 1600x900 60.00 1280x1024 75.02 60.02 1440x900 59.90 1280x800 59.91 1152x864 75.00 1280x720 60.00 50.00 59.94 1024x768 75.03 70.07 60.00 832x624 74.55 800x600 72.19 75.00 60.32 56.25 720x576 50.00 720x480 60.00 59.94 640x480 75.00 72.81 66.67 60.00 59.94 720x400 70.08 VIRTUAL1 disconnected (normal left inverted right x axis y axis)与连接的监视器相对应的文件
/sys/class/drm/card0-HDMI-A-2/status包含单词connected（如预期）。然后我断开 HDMI 电缆。当我检查
/sys/class/drm/card0-HDMI-A-2/status它仍然包含connected.- 当我现在
xrandr再次运行时，它会以某种方式重置我的设置，并且文件会更新以反映正确的状态，即disconnected.
我的问题：如何修复该行为，以便 /sys 文件系统在拔掉电缆后立即正确反映状态？而且我不必打电话xrandr来启动更新。
替代问题：正在xrandr做什么导致 /sys 文件系统更新？这样我也许可以编写一个定期导致更新的小脚本。
在此期间我还查看了udevadm monitor：
monitor will print the received events for:
UDEV - the event which udev sends out after rule processing
KERNEL - the kernel uevent
KERNEL[7260.824844] change /devices/pci0000:00/0000:00:02.0/drm/card0 (drm)
UDEV [7260.825690] change /devices/pci0000:00/0000:00:02.0/drm/card0 (drm)
KERNEL[7280.130646] change /devices/pci0000:00/0000:00:02.0/drm/card0 (drm)
UDEV [7280.138375] change /devices/pci0000:00/0000:00:02.0/drm/card0 (drm)
将 HDMI 电缆插入计算机后，前两行立即出现，但最后两行仅在我运行xrandr步骤 3 中提到的命令时出现。
如果有任何帮助的话，这是我的内核版本：
Linux archy 4.8.13-1-ARCH #1 SMP PREEMPT Fri Dec 9 07:24:34 CET 2016 x86_64 GNU/Linux