How to connect the Due to Ubuntu?

I have successfully compiled my program, and try to upload it to the Arduino Due using BOSSAC (arduino/hardware/tools/bossac.exe). The problem is I get this error:

No device found on /dev/ttyACM0

This is the argument I use to specify the port:

--port=/dev/ttyACM0

It works in the Arduino IDE. I've tried both giving rw to others and running BOSSAC as root.