(without using getty, agetty or the like)
I wanted to create a custom live CD of Ubuntu Linux, with, among other features, a root login shell on the first serial port.
The following command does just that. Default settings are 9600,8n1.
/bin/login -f root > /dev/ttyS0 < /dev/ttyS0 2>&1
Normally this would be added to
/etc/inittab alongside the other TTY lines.
