6.6. No getty
If you are using serial console simply to print console
messages then do not run a getty process
on the serial port.
getty follows a locking convention
that prevents other serial port applications from using the serial
port. Since we do not want other processes to use the serial port,
but are not running getty, manually
create the lock file.
Create a file /var/lock/LCK..ttyS0 to
contain the text 1. This lets other potential
serial port applications know that process 1 has the serial port in
use. Process 1 is always the init
process, and init is always running, so
the serial port is always locked.
The file is created upon each system boot, as lock files are
often cleared when the system boots. A convenient place to create
the lock file is from /etc/rc.serial. It
should contain: