In RedHat, CentOs and Suse and probaly other Linux distributions, the way of enabling and disabling a service at reboot is by using chkconfig. In ubuntu, the way of turning on and off a services at boot is by using update-rc.d. It changes the links for the init scripts.
To start a script in the default run levels:
sudo update-rc.d appname defaults
To remove a script from all runlevels:
sudo update-rc.d appname remove
