udevadm monitor
monitor will print the received events for:
UDEV - the event which udev sends out after rule processing
KERNEL - the kernel uevent

KERNEL[1309366808.454287] add      /devices/pci0000:00/0000:00:1d.7/usb2/2-1 (usb)
KERNEL[1309366808.454492] add      /devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:1.0 (usb)
KERNEL[1309366808.454641] add      /devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:1.0/host6 (scsi)
KERNEL[1309366808.454707] add      /devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:1.0/host6/scsi_host/host6 (scsi_host)
UDEV  [1309366808.469091] add      /devices/pci0000:00/0000:00:1d.7/usb2/2-1 (usb)
UDEV  [1309366808.469908] add      /devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:1.0 (usb)
UDEV  [1309366808.470226] add      /devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:1.0/host6 (scsi)
UDEV  [1309366808.470543] add      /devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:1.0/host6/scsi_host/host6 (scsi_host)
KERNEL[1309366809.455404] add      /devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:1.0/host6/target6:0:0 (scsi)
KERNEL[1309366809.455501] add      /devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:1.0/host6/target6:0:0/6:0:0:0 (scsi)
KERNEL[1309366809.455588] add      /devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:1.0/host6/target6:0:0/6:0:0:0/scsi_disk/6:0:0:0 (scsi_disk)
UDEV  [1309366809.455607] add      /devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:1.0/host6/target6:0:0 (scsi)
UDEV  [1309366809.455804] add      /devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:1.0/host6/target6:0:0/6:0:0:0 (scsi)
UDEV  [1309366809.456085] add      /devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:1.0/host6/target6:0:0/6:0:0:0/scsi_disk/6:0:0:0 (scsi_disk)
KERNEL[1309366809.456163] add      /devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:1.0/host6/target6:0:0/6:0:0:0/scsi_device/6:0:0:0 (scsi_device)
UDEV  [1309366809.456425] add      /devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:1.0/host6/target6:0:0/6:0:0:0/scsi_device/6:0:0:0 (scsi_device)
KERNEL[1309366809.456512] add      /devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:1.0/host6/target6:0:0/6:0:0:0/scsi_generic/sg2 (scsi_generic)
KERNEL[1309366809.456663] add      /devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:1.0/host6/target6:0:0/6:0:0:0/bsg/6:0:0:0 (bsg)
UDEV  [1309366809.457107] add      /devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:1.0/host6/target6:0:0/6:0:0:0/bsg/6:0:0:0 (bsg)
UDEV  [1309366809.457128] add      /devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:1.0/host6/target6:0:0/6:0:0:0/scsi_generic/sg2 (scsi_generic)
KERNEL[1309366809.458157] add      /devices/virtual/bdi/8:16 (bdi)
UDEV  [1309366809.458414] add      /devices/virtual/bdi/8:16 (bdi)
KERNEL[1309366809.462150] add      /devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:1.0/host6/target6:0:0/6:0:0:0/block/sdb (block)
KERNEL[1309366809.462172] add      /devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:1.0/host6/target6:0:0/6:0:0:0/block/sdb/sdb1 (block)
KERNEL[1309366809.462189] add      /devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:1.0/host6/target6:0:0/6:0:0:0/block/sdb/sdb2 (block)
KERNEL[1309366809.462206] add      /devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:1.0/host6/target6:0:0/6:0:0:0/block/sdb/sdb3 (block)
UDEV  [1309366809.545202] add      /devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:1.0/host6/target6:0:0/6:0:0:0/block/sdb (block)
UDEV  [1309366809.611082] add      /devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:1.0/host6/target6:0:0/6:0:0:0/block/sdb/sdb3 (block)
UDEV  [1309366809.745529] add      /devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:1.0/host6/target6:0:0/6:0:0:0/block/sdb/sdb1 (block)
UDEV  [1309366809.749305] add      /devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:1.0/host6/target6:0:0/6:0:0:0/block/sdb/sdb2 (block)