Udevadm info starts with the device specified by the devpath and then walks up the chain of parent devices. It prints for every device found, all possible attributes in the udev rules key format. A rule to match, can be composed by the attributes of the device and the attributes from one single parent device. SUBSYSTEM=="usb" DRIVER=="usb" ATTR{authorized}=="1" ATTR{avoid_reset_quirk}=="0" ATTR{bConfigurationValue}=="1" ATTR{bDeviceClass}=="00" ATTR{bDeviceSubClass}=="00" ATTR{bMaxPacketSize0}=="64" ATTR{bMaxPower}=="500mA" ATTR{bNumConfigurations}=="1" ATTR{devpath}=="1" ATTR{ltm_capable}=="no" ATTR{maxchild}=="0" ATTR{quirks}=="0x0" ATTR{removable}=="unknown" ATTR{speed}=="480" ATTR{version}==" 2.00" SUBSYSTEMS=="usb" DRIVERS=="usb" ATTRS{authorized}=="1" ATTRS{authorized_default}=="1" ATTRS{avoid_reset_quirk}=="0" ATTRS{bConfigurationValue}=="1" ATTRS{bDeviceClass}=="09" ATTRS{bDeviceProtocol}=="01" ATTRS{bDeviceSubClass}=="00" ATTRS{bMaxPacketSize0}=="64" ATTRS{bMaxPower}=="0mA" ATTRS{bNumConfigurations}=="1" ATTRS{bNumInterfaces}==" 1" ATTRS{bmAttributes}=="e0" ATTRS{configuration}=="" ATTRS{devnum}=="1" ATTRS{devpath}=="0" ATTRS{idProduct}=="0002" ATTRS{idVendor}=="1d6b" ATTRS{ltm_capable}=="no" ATTRS{maxchild}=="2" ATTRS{product}=="xHCI Host Controller" ATTRS{quirks}=="0x0" ATTRS{removable}=="unknown" ATTRS{speed}=="480" ATTRS{version}==" 2.00" SUBSYSTEMS=="pci" DRIVERS=="xhci_hcd" ATTRS{broken_parity_status}=="0" ATTRS{class}=="0x0c0330" ATTRS{consistent_dma_mask_bits}=="64" ATTRS{d3cold_allowed}=="1" ATTRS{driver_override}=="(null)" ATTRS{enable}=="1" ATTRS{local_cpulist}=="0-3" ATTRS{local_cpus}=="f" ATTRS{msi_bus}=="1" ATTRS{numa_node}=="-1" ATTRS{subsystem_vendor}=="0x1043" ATTRS{vendor}=="0x1022" looking at parent device '/devices/pci0000:00': KERNELS=="pci0000:00" SUBSYSTEMS=="" DRIVERS==""