Flashing arduino mega2560 firmware from OctoPi

I have a clone Arduino Mega2560 that I keep having to make changes to the firmware for my 3D printer.  Most of the steps are straight forward:

1. Make changes to firmware in Arduino software.
2. Save as hex
3. sftp/scp the file to the Raspberry Pi

The last step was the one that gave me so much grief.  For my particular setup, here's the command that works:

avrdude -p m2560 -c stk500v2 -P /dev/ttyUSB0 -D -U flash:w:Marlin.ino.mega.hex:i