On occasion I need to know the gritty details of a USB device attached to Linux. Fortunately this is fairly trivial once you know what tools to use and how to use them. This is just some quick notes (namely for myself) as I don't do this often enough to remember all of the details.
Using lsusb (or lsusb -v for USB descriptor information) is as simple as the command, so I only mention it for awareness.
Depending on the information that might be needed, lsusb and/or udevinfo can be used. Note however, under Ubuntu udevinfo is udevadm (and info can be passed as an argument). In my case I have attached a USB FLASH drive to the Ubuntu host. Running dmesg will print the kernel message buffer and at the end I should see that it connected. In my case it has attached as a SCSI drive [sdb] and the device node should have been created /dev/sdb. More information on drive naming in Linux can be found at:
http://tldp.org/HOWTO/Partition-Mass-Storage-Definitions-Naming-HOWTO/x99.html
Now we can use the path of the device node as input to udevadm info as follows (and output for my example):
Using lsusb (or lsusb -v for USB descriptor information) is as simple as the command, so I only mention it for awareness.
Depending on the information that might be needed, lsusb and/or udevinfo can be used. Note however, under Ubuntu udevinfo is udevadm (and info can be passed as an argument). In my case I have attached a USB FLASH drive to the Ubuntu host. Running dmesg will print the kernel message buffer and at the end I should see that it connected. In my case it has attached as a SCSI drive [sdb] and the device node should have been created /dev/sdb. More information on drive naming in Linux can be found at:
http://tldp.org/HOWTO/Partition-Mass-Storage-Definitions-Naming-HOWTO/x99.html
Now we can use the path of the device node as input to udevadm info as follows (and output for my example):
$ udevadm info -q all -n /dev/sdb
P: /devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.2/1-1.2.1/1-1.2.1.4/1-1.2.1.4.1/1-1.2.1.4.1:1.0/host10/target10:0:0/10:0:0:0/block/sdb
N: sdb
S: disk/by-id/usb-Lexar_USB_Flash_Drive_X5O6JNLCL623EFHRYD0A-0:0
S: disk/by-path/pci-0000:00:1a.0-usb-0:1.2.1.4.1:1.0-scsi-0:0:0:0
E: DEVLINKS=/dev/disk/by-id/usb-Lexar_USB_Flash_Drive_X5O6JNLCL623EFHRYD0A-0:0 /dev/disk/by-path/pci-0000:00:1a.0-usb-0:1.2.1.4.1:1.0-scsi-0:0:0:0
E: DEVNAME=/dev/sdb
E: DEVPATH=/devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.2/1-1.2.1/1-1.2.1.4/1-1.2.1.4.1/1-1.2.1.4.1:1.0/host10/target10:0:0/10:0:0:0/block/sdb
E: DEVTYPE=disk
E: ID_BUS=usb
E: ID_INSTANCE=0:0
E: ID_MODEL=USB_Flash_Drive
E: ID_MODEL_ENC=USB\x20Flash\x20Drive\x20
E: ID_MODEL_ID=a788
E: ID_PART_TABLE_TYPE=dos
E: ID_PATH=pci-0000:00:1a.0-usb-0:1.2.1.4.1:1.0-scsi-0:0:0:0
E: ID_PATH_TAG=pci-0000_00_1a_0-usb-0_1_2_1_4_1_1_0-scsi-0_0_0_0
E: ID_REVISION=1100
E: ID_SERIAL=Lexar_USB_Flash_Drive_X5O6JNLCL623EFHRYD0A-0:0
E: ID_SERIAL_SHORT=X5O6JNLCL623EFHRYD0A
E: ID_TYPE=disk
E: ID_USB_DRIVER=usb-storage
E: ID_USB_INTERFACES=:080650:
E: ID_USB_INTERFACE_NUM=00
E: ID_VENDOR=Lexar
E: ID_VENDOR_ENC=Lexar\x20\x20\x20
E: ID_VENDOR_ID=05dc
E: MAJOR=8
E: MINOR=16
E: SUBSYSTEM=block
E: UDEV_LOG=3
E: UDISKS_PARTITION_TABLE=1
E: UDISKS_PARTITION_TABLE_COUNT=1
E: UDISKS_PARTITION_TABLE_SCHEME=mbr
E: UDISKS_PRESENTATION_NOPOLICY=0
E: USEC_INITIALIZED=11740264586
Specifically, I am looking for the device path:
E: DEVPATH=/devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.2/1-1.2.1/1-1.2.1.4/1-1.2.1.4.1/1-1.2.1.4.1:1.0/host10/target10:0:0/10:0:0:0/block/sdb
Now we can start with the specified device and let udevadm walk up the chain of parent devices listing out usefull details for each in the chain. This not only gives us the details of what it is connected, but how it is connected and the details of what it is connected to. The following command will list the chain for the example device from above (output is not listed for brevity):
$ udevadm info -a -p /devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.2/1-1.2.1/1-1.2.1.4/1-1.2.1.4.1/1-1.2.1.4.1:1.0/host10/target10:0:0/10:0:0:0/block/sdb That's about all there is to it. Of course udevadm can do much more when needed. To find out how check out:
http://linux.die.net/man/8/udevadm
http://linux.die.net/man/8/udevadm
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