I have a laptop, and I save the following to /etc/udev/hwdb.d/90-custom-keyboard.hwdbkeyboard:usb:v*p*keyboard:dmi:bvn*:bvr*:bd*:svn*:pn*:pvr* KEYBOARD_KEY_1a=a KEYBOARD_KEY_1b=band run$ sudo udevadm hwdb --update && sudo udevadm triggerin order to refresh the key mappings. Now, this is a dummy case that should replace the [ and ] keys with a and b for any USB or dmi keyboard. However, I only get the changes on my laptop's keyboard, and not my other keyboards (a wired and another wireless USB keyboard). I am sure that the same scancodes are sent for all the keyboards I have, regarding the keys I want to remap.I am using Arch Linux and this is the tutorial I have been looking at.What do I need to do to make the remapping valid for all USB keyboards that are to be plugged in in the future? 
udev keyboard remapping with hwdb for secondary keyboards
keyboard;udev