documentation/Examples/Debian/Enable Serial Console.md

Procedure

1. Open /etc/default/grub in nano, e.g.

    nano /etc/default/grub
   

2. Modify the line GRUB_CMDLINE_LINUX_DEFAULT to include console=ttyS0, e.g.

    GRUB_CMDLINE_LINUX_DEFAULT="quiet console=ttyS0"
   

3. Update grub via the update-grub command

4. If using Proxmox, be sure to add a hardware serial port

   !!! info "Note"

    If done correctly, your Debian virtual machine in Proxmox will have a text console accessible via xterm.js
   

Sources

http://notesofaprogrammer.blogspot.com/2020/05/enabling-serial-console-on-debian-linux.html