Good day or night. Help me please. I have armbian. And there are - systemd. I do not know how to set up my usb keyboard to make it work with two displays at once. With tty1 and ttyS0 at the same time. To become a clone tty1 -> ttyS0. Tell me, how do I configure it?

man screen

I seem to remember that screen can reattach itself to an existing session, duplicating it.

 

best, gnasch

Thank you so much! I definitely try it. Do you know if I can do it at the level of the system settings? Because I do not have access to something like ttyS0 input, and the display is precisely on something like ttyS0, and there is no display on tty1. Now I go in through ssh, and I would like to use just the display on the ttyS0 and usb keyboard.

The question remains open.

try conspy - virtual console spy tool

 

DESCRIPTION
       Conspy  allows  the  user  to take control of a Linux virtual console.  The user can see what is displayed on the console and
       their keystrokes are sent to it.