modifierkeys

A command line tool for macOS.

This is a modern version of the Carbon keys.m and possibly other similar programs.

The program returns the state of the following modifier keys on macOS:

• Caps Lock (⇪)
• Function (fn)
• Control (⌃)
• Option (⌥)
• Shift (⇧)
• Command (⌘)

With all modifier keys down, it will return the string: capslock-function-control-option-shift-command. The order will remain the same, no matter which keys are down. For example, with only Control and Command down, the output is: control-command.

The order control-option-shift-command corresponds to the traditional order as used by Apple.¹

Usage example in a shell script, with sample output

#!/usr/bin/env zsh

# To give you time to hold down keys after launching the program
sleep 2

state=$(modifierkeys)
output="Complete return string: ${state}\n"

if [[ $state == option ]]; then
	output+="Only Option down."
elif [[ $state == option-shift ]]; then
	output+="Option and Shift down, nothing else."
elif [[ $state == *option*command ]]; then
	output+="Option and Command down, possibly other keys too.\n"
elif [[ $state == *option* ]]; then
	output+="Option down, possibly other keys too."
fi

echo "${output}"

Build

Compile with swiftc <path/to/modifierkeys.swift> or try the binary from Releases, if available.

Tested on macOS Ventura and Sonoma (Intel).

---

I'm not too familiar with Swift and the macOS API, so any suggestions for improvements are welcome.

Footnotes

1. Example doc: https://support.apple.com/en-us/HT201236
   Opinion: https://leancrew.com/all-this/2017/11/modifier-key-order/ ↩