for Mac OS users with brew, you can run "brew install avrdude".
To find your ports you can run "ls /dev/{tty,cu}.*", which will list something like "/dev/tty.usbmodem31101"
Your terminal command would look something like:
avrdude -p ATmega32u4 -P /dev/cu.usbmodem31101 -c avr109 -U flash:w:adb.hex
