We will need this information later on, to be able to assign a given keyboard/mouse to a given X-server/Display.
To find the PHYS ID's (the addresses) or the name(quite oft it differs from the one labeled on the device) of your input devices you have to read the file /proc/bus/input/devices.
Here is what I have:
[svetljo@svetljo How-To]# cat /proc/bus/input/devices I: Bus=0011 Vendor=0002 Product=0002 Version=0034 N: Name="PS2++ Logitech Wheel Mouse" P: Phys=isa0060/serio1/input0 H: Handlers=mouse0 ts0 B: EV=7 B: KEY=f0000 0 0 0 0 0 0 0 0 B: REL=103 I: Bus=0011 Vendor=0001 Product=0002 Version=ab02 N: Name="AT Set 2 keyboard" P: Phys=isa0060/serio0/input0 H: Handlers=kbd B: EV=120003 B: KEY=4 2000000 8061f9 fbc9d621 efdfffdf ffefffff ffffffff fffffffe B: LED=7 I: Bus=0003 Vendor=046d Product=c303 Version=0700 N: Name="Logitech USB Keyboard" P: Phys=usb-00:10.1-1.1/input0 H: Handlers=kbd B: EV=120003 B: KEY=10000 7f ffe00000 7ff ffbeffdf ffffffff ffffffff fffffffe B: LED=7 I: Bus=0003 Vendor=046d Product=c303 Version=0700 N: Name="Logitech USB Keyboard" P: Phys=usb-00:10.1-1.1/input1 H: Handlers=kbd B: EV=100003 B: KEY=1078 1800d100 1e0000 0 0 0 I: Bus=0003 Vendor=05fe Product=0011 Version=0000 N: Name="Cypress Sem. PS2/USB Browser Combo Mouse" P: Phys=usb-00:10.1-1.2/input0 H: Handlers=mouse1 ts1 B: EV=7 B: KEY=1f0000 0 0 0 0 0 0 0 0 B: REL=103
/proc/bus/input/devices will provide the needed information for all devices except USB multimedia/office keyboards.
For such USB multimedia/office keyboards you will have to gather additional information, for example with the help of lsusb.
Under Ruby-2.6 for usb devices it will look like "usb-0000:00:10.x" not "usb-00:10.x"
First we have to find the address of the USB keyboard:
[root@svetljo How-To]# lsusb Bus 004 Device 001: ID 0000:0000 Bus 003 Device 001: ID 0000:0000 Bus 003 Device 002: ID 0409:55ab NEC Corp. Hub [iMac kbd] Bus 003 Device 003: ID 046d:c303 Logitech, Inc. Bus 003 Device 004: ID 05fe:0011 Chic Technology Corp. Browser Mouse Bus 002 Device 001: ID 0000:0000 Bus 001 Device 001: ID 0000:0000
Here, my USB Logitech keyboard is Device 003 on Bus 003.
Now we run lsusb with arguments -v -s [your USB keyboard device id in form Bus:Device], in my case, lsusb -v -s 003:003.
........
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 3 Human Interface Devices
bInterfaceSubClass 1 Boot Interface Subclass
bInterfaceProtocol 1 Keyboard
iInterface 0
........
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 3 Human Interface Devices
bInterfaceSubClass 0 No Subclass
bInterfaceProtocol 0 None
iInterface 0
........
So my USB keyboard has two interfaces (see bInterfaceNumber); the first one is the real keyboard (bInterfaceProtocol 1 Keyboard), the second (bInterfaceProtocol 0 None) - the additional keys. Hence the real USB keyboard is:
..... N: Name="Logitech USB Keyboard" P: Phys=usb-00:10.1-1.1/input0 H: Handlers=kbd .....
The “P: Phys=” field (the physical descriptor/address) consorts of:
Bus type: “usb”
PCI function of the USB controller: “00:10.1 ” ( for Ruby-2.6 "0000:00:10.1")
USB device id: “1.1”
The string: “/input”
Interface number: “0”