The file /etc/rc.d/rc.local script is run by init at boot
time, after all other initialization is complete, and whenever you
change runlevels. You can add additional initialization commands
here. For instance, you may want to start up additional daemons or
initialize a printer.
In addition, if you require serial port setup,
you can create and edit /etc/rc.serial, and it will be
executed automatically at boot time. This script can run a number of
setserial commands to specially configure the
system's serial ports. See the setserial man page for
more information.
The default /etc/rc.d/rc.local simply creates a
login banner with your kernel version and machine type.
