I have a USB-to-Serial converter for my Mac I want to use to connect to an Ubuntu server that outputs all its console over its serial port (it's an APU2 machine with no graphics output). On the server /etc/default/grub contains the following lines:

GRUB_CMDLINE_LINUX="gfxpayload=text fb=false console=ttyS0,115200n8"
# Uncomment to disable graphical terminal (grub-pc only)
GRUB_SERIAL_COMMAND="serial --speed=115200 --unit=0 --word=8 --parity=no --stop=1"

The USB-to-Serial shows up as /dev/tty.usbserial on my Mac. What do I state the port # as in grub?

  • Is I read this I come to the conclusion that it has nothing todo with MAC. Why is it in the title? OR have I miss-understood. (I realise that the MAC is connected to the other end, but this has nothing to do with configuring grub) Are you running grub on the MAC (is it just MAC hardware)? the question is unclear. Aug 26, 2019 at 9:11
  • As I was thinking about this in the background, I realized it has nothing to do with the APU2. Since the grub exists on that, it will always define the port of that machine. I need some sort of terminal program on my Mac that would need to be configured to use the /dev/tty.usbserial. Let me know if I should delete the Q altogether. Aug 26, 2019 at 9:27

1 Answer 1


try this:

sudo cu -s 115200 -l /dev/tty.usbserial

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