cat > /etc/udev/rules.d/99-ktec_ergodone.rules <<EOF
SUBSYSTEM=="usb", ATTRS{idVendor}=="1209", ATTRS{idProduct}=="2327", MODE="0664", GROUP="plugdev"
EOF
udevadm control --reload-rules
Don't forget to add your regular user to plugdev group! so you can flash without using root permissions.
# examples
hid_bootloader_cli -mmcu=atmega32u4 ktec_ergodone_droberin.hex
hid_bootloader_cli -mmcu=atmega32u4 ktec_ergodone_default.hex