To know which USB devices are installed the following command can be used in a terminal:
lsusb
The output of this command shows if the USB device is correctly connected and what the vendor and model of the USB device is. This command is a very good tool to find out if Ubuntu sees and recognizes all USB devices onboard of your system. As an example below the output of the command after running it in a terminal on my system:
Bus 001 Device 002: ID 03f0:8a11 Hewlett-PackardÂ
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 003 Device 003: ID 145f:0176 Trust Isla Keyboard
Bus 003 Device 002: ID 046d:c043 Logitech, Inc. MX320/MX400 Laser Mouse
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
It is possible that USB hardware devices cannot be detected by Linux or is detected, but not properly recognized by Linux for any reasons. The device will be shown like this example:
Bus 001 Device 002: ID 03f0:8a11 Hewlett-Packard
By using the ID code, the full device name and type can be found on this site: http://www.linux-usb.org/usb.ids. When visiting this site, best to do is using the search function of the web browser. The ID code is a combination of two separate ID codes: an ID code for the device vendor before the colon and an ID code for the device model after the colon, both device ID codes consist of a combination of numbers and letters. When searching on the website, select the ID code and enter this code in the search field of the browser.
Above in the output you can see in the first line that a HP device is connected to my system:
03f0 is the USB Device ID code for Hewlett-Packard (HP)
8a11 is the USB Device ID code for the model which, in this case, is unknown.
When searching on the website of linux-usb.org, no entry can be found for 8a11. But that does not mean that my HP device is not detected or recognized by Linux Mint. The device is a HP Photosmart Wireless B110 all-in-one printer and works flawless with Mint 17 MATE!