preseed/stretch/commands/late_commands.d/enable_serial_console

   1 #!/bin/sh
   2 echo "Enabling the serial console..."
   3 if [ -f /etc/default/grub ]; then
   4   #683124/#769406 requires the cmdline patch, and #444026 is for GRUB_TERMINAL:
   5   sed -i -e '/^GRUB_CMDLINE_LINUX=/s/"$/ console=tty0 console=ttyS0,115200n8&/' \
   6         -e '/^GRUB_CMDLINE_LINUX=/s/=" /="/' \
   7         -e '/^GRUB_TERMINAL=/s/serial/"& console"/' \
   8         /etc/default/grub
   9   update-grub
  10 fi
  11 if [ -f /etc/inittab ]; then
  12   sed -i '/ttyS0/s/^#//;/ttyS0/s/9600 vt100/115200 linux/' /etc/inittab
  13 else
  14   echo "Not setting up a TTY on the serial port, presumably systemd will..."
  15 fi