12.3. System Startup and Shutdown

During system startup, a series of scripts are run to start the services that you need. These include scripts to start network interfaces, mount directories, and monitor your system. Most of these scripts are run from subdirectories of /etc/rc.d. The program that starts most of these services up when you boot and stops them when you shut down is the /etc/rc.d/rc script. The following sections describe run-level scripts and what you can do with them.

12.3.1. Starting run-level scripts

As previously mentioned, the /etc/rc.d/rc script is integral to the concept of run levels. Any change of run level causes the script to be executed, with the new run level as an argument. Here's a quick run-down of what the /etc/rc.d/rc script does: