update-rc.d is the utility that Debian provides to manage SystemV init scripts. If you are familiar with Redhat's chkconfig then you're half way to understanding how to use it. Here's how: Say you have a new service called "waffles" that you would like to start at boot time. Make sure that the file "/etc/init.d/waffles" exists. If this was debian package installed via apt you can almost be sure that this exists, if this was an installation from source, you may need to create your own init script or find a provided example, but this is outside of our scope. So let's say that this init script exists. Here is the simple command that you can type to make your service run at boot time.
# update-rc.d waffles defaults
This will make sure that when your system reaches runlevel 2, 3, 4 or 5 that the waffles service will start up and that in runlevel 0, 1 or 6 it will be stopped. So you're done with your waffles and you would like to stop them from starting up tomorrow morning when you reboot? Just issue this simple command to remove it from starting up at boot time:
# update-rc.d waffles remove
It's as simple as that, but sometimes you would like to make your setup a bit more complicated. Say for instance you don't want waffles to start up in runlevels 2 or 3? You could run the following command:
# update-rc.d waffles start 45 stop 01236
Waffles will start up when your system reaches runlevels 4 or 5, but stop at 0, 1, 2, 3 or 6. One last thing though, if you do not like the way update-rc.d functions or if you would just prefer a graphical interface, try installing rcconf ( apt-get install rcconf ). This tool is a graphical interface that can be used from the shell to configure your System V style init scripts.