摘自：https://blog.csdn.net/wandersky0822/article/details/110202371
通过使用PF_NETLINK类型建立的socket， 确实能检测到USB口的变化，这个东西太好了，做U盘自动检测，自动挂载就靠它了。 眼前豁然开朗
当插入U盘时，打印如下信息：
add@/devices/pci0000:00/0000:00:15.0/0000:03:00.0/usb3/3-2
add@/devices/pci0000:00/0000:00:15.0/0000:03:00.0/usb3/3-2/3-2:1.0
add@/devices/pci0000:00/0000:00:15.0/0000:03:00.0/usb3/3-2/3-2:1.0/host35
add@/devices/pci0000:00/0000:00:15.0/0000:03:00.0/usb3/3-2/3-2:1.0/host35/scsi_host/host35
add@/devices/pci0000:00/0000:00:15.0/0000:03:00.0/usb3/3-2/3-2:1.0/host35/target35:0:0
add@/devices/pci0000:00/0000:00:15.0/0000:03:00.0/usb3/3-2/3-2:1.0/host35/target35:0:0/35:0:0:0
add@/devices/pci0000:00/0000:00:15.0/0000:03:00.0/usb3/3-2/3-2:1.0/host35/target35:0:0/35:0:0:0/scsi_disk/35:0:0:0
bind@/devices/pci0000:00/0000:00:15.0/0000:03:00.0/usb3/3-2/3-2:1.0/host35/target35:0:0/35:0:0:0
add@/devices/pci0000:00/0000:00:15.0/0000:03:00.0/usb3/3-2/3-2:1.0/host35/target35:0:0/35:0:0:0/scsi_generic/sg2
add@/devices/pci0000:00/0000:00:15.0/0000:03:00.0/usb3/3-2/3-2:1.0/host35/target35:0:0/35:0:0:0/bsg/35:0:0:0
add@/devices/virtual/bdi/8:48
add@/devices/pci0000:00/0000:00:15.0/0000:03:00.0/usb3/3-2/3-2:1.0/host35/target35:0:0/35:0:0:0/block/sdd
add@/devices/pci0000:00/0000:00:15.0/0000:03:00.0/usb3/3-2/3-2:1.0/host35/target35:0:0/35:0:0:0/block/sdd/sdd1
当拨出U盘时，打印如下信息：
remove@/devices/pci0000:00/0000:00:15.0/0000:03:00.0/usb3/3-2/3-2:1.0/host35/target35:0:0/35:0:0:0/bsg/35:0:0:0
remove@/devices/pci0000:00/0000:00:15.0/0000:03:00.0/usb3/3-2/3-2:1.0/host35/target35:0:0/35:0:0:0/scsi_generic/sg2
remove@/devices/pci0000:00/0000:00:15.0/0000:03:00.0/usb3/3-2/3-2:1.0/host35/target35:0:0/35:0:0:0/scsi_device/35:0:0:0
remove@/devices/virtual/bdi/8:48
remove@/devices/pci0000:00/0000:00:15.0/0000:03:00.0/usb3/3-2/3-2:1.0/host35/target35:0:0/35:0:0:0/block/sdd
unbind@/devices/pci0000:00/0000:00:15.0/0000:03:00.0/usb3/3-2/3-2:1.0/host35/target35:0:0/35:0:0:0
remove@/devices/pci0000:00/0000:00:15.0/0000:03:00.0/usb3/3-2/3-2:1.0/host35/target35:0:0
remove@/devices/pci0000:00/0000:00:15.0/0000:03:00.0/usb3/3-2/3-2:1.0/host35/scsi_host/host35
remove@/devices/pci0000:00/0000:00:15.0/0000:03:00.0/usb3/3-2/3-2:1.0/host35
unbind@/devices/pci0000:00/0000:00:15.0/0000:03:00.0/usb3/3-2/3-2:1.0
remove@/devices/pci0000:00/0000:00:15.0/0000:03:00.0/usb3/3-2/3-2:1.0
unbind@/devices/pci0000:00/0000:00:15.0/0000:03:00.0/usb3/3-2
remove@/devices/pci0000:00/0000:00:15.0/0000:03:00.0/usb3/3-2
在电脑虚拟机上可以用， 但是在我的树莓派上却用不了，我怀疑怀疑还是系统的原因，因此采用这种高大上的办法好像适用性不是很广泛，
于是我又老实了把 检测access /dev/sda1 节点， 检测到之后，再挂载的办法，也实现了。还是这个办法保险。