I am running a simple script on the Arduino that is supposed to output to serial (/dev/ttyACM0). It works great in the Arduino IDE and can even been seen by running: sudo tail -f /dev/ttyACM0 However, whenever I reboot the board and try to run sudo tail -f /dev/ttyACM0 without first running in the IDE, nothing shows up. If I open the IDE and open the serial monitor tool, it works fine. I can then close that window and run the tail command and it works. It appears that nothing is written to the serial port until the serial monitor tool is run in the IDE. Everything I can find in the Arduino and Udoo docs seem to indicate that the Arduino will run the last loaded script on boot. What's going on here? Is there something the IDE is doing to activate the serial port?