Serial Console on Newer Ubuntu Systems

This is another one of those boring reference blog posts on things you don't do very often so you forget how to do them.

Starting with Edgy, Ubuntu uses upstart instead of good old init so you no longer use /etc/inittab to enable serial consoles.

See SerialConsoleHowto for details, but basically what basically what you do is create a file in /etc/event.d for all the devices you want to spawn a getty on.

root@cm1208:/etc/event.d# ls
control-alt-delete  rc1  rc4  rc-default   sulogin  tty3  tty6
logd                rc2  rc5  rcS          tty1     tty4  ttyS0
rc0                 rc3  rc6  rcS-sulogin  tty2     tty5
root@cm1208:/etc/event.d# 

Looking inside ttyS0

# ttyS0 - getty
#
# This service maintains a getty on ttyS0 from the point the system is
# started until it is shut down again.

start on runlevel 2
start on runlevel 3
start on runlevel 4
start on runlevel 5

stop on runlevel 0
stop on runlevel 1
stop on runlevel 6

respawn
exec /sbin/getty 115200 ttyS0

and you can see the process running

root@cm1208:~# ps aux | grep ttyS0
root       547  0.0  0.0   3004   756 pts/2    R+   09:40   0:00 grep ttyS0
root      4239  0.0  0.0   1716   512 ttyS0    Ss+  Oct23   0:00 /sbin/getty 115200 ttyS0