The Init Process - Novell LINUX ENTERPRISE SERVER 11 - ADMINISTRATION Administration Manual

process are written to INITRD_MODULES in /etc/sysconfig/kernel.
These names are used to generate a custom initramfs that is needed to boot the
system. If the modules are not needed for boot but for coldplug, the modules are
written to /etc/sysconfig/hardware/hwconfig-*. All devices that are
described with configuration files in this directory are initialized in the boot process.
Loading the Installation System or Rescue System
As soon as the hardware has been properly recognized, the appropriate drivers have
been loaded, and udev has created the device special files, init starts the installation
system, which contains the actual YaST installer, or the rescue system.
Starting YaST
Finally, init starts YaST, which starts package installation and system configuration.

7.2 The init Process

The program init is the process with process ID 1. It is responsible for initializing the
system in the required way. init is started directly by the kernel and resists signal 9,
which normally kills processes. All other programs are either started directly by init or
by one of its child processes.
init is centrally configured in the /etc/inittab file where the runlevels are defined
(see Section 7.2.1, "Runlevels"
daemons are available in each of the runlevels. Depending on the entries in /etc/
inittab, several scripts are run by init. By default, the first script that is started after
booting is /etc/init.d/boot. Once the system initialization phase is finished, the
system changes the runlevel to its default runlevel with the /etc/init.d/rc script.
For reasons of clarity, these scripts, called init scripts, all reside in the directory /etc/
init.d (see
Section 7.2.2, "Init Scripts"
The entire process of starting the system and shutting it down is maintained by init.
From this point of view, the kernel can be considered a background process whose task
is to maintain all other processes and adjust CPU time and hardware access according
to requests from other programs.
(page 66)). The file also specifies which services and
(page 68)).
Booting and Configuring a Linux System 65