On a 2017 MacBook Pro 15", I want symmetry in my three modifier keys (ctrl, option, cmd), i.e. what's available to my right hand would be mirror-symmetrical to what's available to my left. The best way to achieve this would be if I could remap the left-arrow (←) key to ctrl. Left-arrow sits directly in line with my right pinky and I don't use it. Is this possible in iTerm (or another emulator), or at the MacOS level?

(I know for sure that remapping at the emulator level is desirable to me. I'm not as sure that I never use the arrow keys in MacOS more broadly, but I'm sure enough to try it.)

I've seen a lot about remapping keys, but so far only that modifiers can be remapped to other modifiers, and other keys to other keys or macros. Since left-arrow (←) isn't already a modifier, I don't see how to make it serve as ctrl. Or is there hardware or firmware standing in the way?

3 Answers 3


You can use hidutil to do this system-wide. Left arrow to control is

/usr/bin/hidutil property --set '{"UserKeyMapping":[{ "HIDKeyboardModifierMappingSrc": 0x700000050, "HIDKeyboardModifierMappingDst": 0x7000000E4}]}'

After further digging, and also (for a different keyboard situation) looking into remapping the fn key for similar reasons, I've concluded that this is probably not possible without at least extra software and perhaps a firmware mod.

This post on Super User was helpful: https://superuser.com/questions/65/remap-fn-to-another-key

  • You don't need firmware - the software yiou need is karabinier-elements
    – mmmmmm
    Commented Feb 13, 2022 at 11:02
  • Karabiner-Elements is great software. But simple modifications can be done with the builtin hidutil command. And fn is a special case, which even Karabiner-Elements can't handle for all keyboards: Karabiner-Elements cannot modify the fn key on non-Apple keyboards such as Logitech keyboards.
    – Volsk
    Commented Mar 15, 2022 at 13:47

You can use Karabiner Elements to remap keys on macOS.

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