This file is to execute comands at startup. The servicestart running through /etc/init.d/rc.local
In this example it runs inadyn to update the dyndns.org service.
#!/bin/sh -e
#
# /etc/rc.local
#
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
#
# In order to enable or disable this script just change the execution
# bits.
#
# By default this script does nothing.
inadyn
exit 0