How to assign a key remapping to specific device using hidutil

Question

As seen in this article from Apple, you can remap a key from the command line in OS Sierra with something like:

hidutil property --set '{"UserKeyMapping": 
  [{"HIDKeyboardModifierMappingSrc":0x700000054,
    "HIDKeyboardModifierMappingDst":0x700000067
  }]
}'

Is it possible to assign this change only to a specific keyboard device, e.g. if you want to map one device to the output of a second, but not affect the function of the second?

The article is no longer updated and there appears to be no current documentation of how the command works.

Answer 1

I'm not quite sure what you mean by "if you want to map one device to the output of a second, but not affect the function of the second?", but the rest of your question sounds like you just want to remap a specific external device. This can be accomplished with the following command:

hidutil property --matching '{"ProductID":0x123}' --set '{"UserKeyMapping": 
 [{"HIDKeyboardModifierMappingSrc":0x700000054,
   "HIDKeyboardModifierMappingDst":0x700000067
 }]
}'

You'll need to determine your specific ProductID and insert it into the command above. You can find ProductIDs for internal and external devices at the following location:

Apple icon > About This Mac > System Report > USB (under Hardware section in left panel)

These changes will be reverted after each restart. In order to make this fix permanent, follow the solution provided in this answer.