Configuration of Init under Debian GNU/Linux

Most Unix versions have a file here that describes how the scripts
in this directory work, and how the links in the /etc/rc?.d/ directories
influence system startup/shutdown.

For Debian, this information is contained in the policy manual, chapter 10.3:
system run levels. The home site for the Debian Policy Manual is at

http://www.debian.org/doc/debian-policy/

The Debian Policy Manual is also available in the Debian package
`debian-policy'. When this package is installed, the policy manual can be
found in directory /usr/share/doc/debian-policy. If you have a web server
and a browser installed you can probably read it at
http://localhost/doc/debian-policy/

Make sure you have at least version 3.5.2.0 of the policy manual.

Some more detailed info can also be found in /usr/share/doc/sysvinit.