PLD contains highly modularized kernel. All kernel-supported device drivers that can be compiled as a module are compiled in this way. To support devices available in the system, proper modules must be loaded into the kernel. That can be done primarily in four ways: They can be loaded by hand with modprobe or insmod command (the least convenient method) They can be loaded at boot-up by some extra script (e.g. /etc/rc.d/init/rc.local). Some devices (mainly disk interfaces) need support at a very, very early stage of system boot-up. Modules for these devices must be loaded from so-called initrd (see more in ) Finally, they can be loaded automatically, when they are needed, by kmod daemon. The latter method is most convenient, although not every device can be supported like that. Kmod needs information what module should be associated to particular devices. During installation process the installer takes care about setting proper initrd, and may also put some entries into /etc/modules.conf. (e.g. aliases for network devices), but in general this file should be filled in by the administrator. Some typical settings in /etc/modules.conf: # Use kernel module 3c509 (3Com 509/509b adapter) as a driver for # first ethernet device (eth0): alias eth0 3c509 # Use kernel module aic7xxx to handle SCSI hostadapter: scsi_hostadapter aic7xxx See modules.conf 5 for details.

fstab: disks removable media: CD, diskettes etc user access automounter LVM? journaling? raid?

The file /etc/inittab is read by init process to control system behavior in particular runlevel. Full description of this file can be found in inittab 5 What this file usually contains: Default runlevel - the runlevel used when init is invoked without parameters (e.g. during system startup). Runlevels are described in . Default runlevel is given in the form: id:3:initdefault: Here the digit 3 indicates use of runlevel 3. This can be changed to any other valid runlevel. Instructions to run getty on consoles. They look like that: 1:12345:respawn:/sbin/mingetty --noclear tty1 One of possible situations when this needs to be changed is when we want console on serial port (see e.g. ). Invocation of proper init scripts. These are lines like this: si::sysinit:/etc/rc.d/rc.sysinit l0:0:wait:/etc/rc.d/rc 0 This rarely needs to be changed. Handling special events like Ctrl-Alt-Del keystroke. The line looks like this: ca::ctrlaltdel:/sbin/shutdown -t3 -r now The command run at Ctrl-Alt-Del event can be replaced here, e.g. one can change shutdown -r to shutdown -h to get the halt instead reboot.

Directory /etc/sysconfig contains several files that are used by rc-scripts (system startup scripts located in /etc/rc.d). Those files defines basic properties of the system.

File /etc/sysconfig/console contains basic console settings. After modifying config file, issue /etc/rc.d/init.d/console restart if you want the changes to take effect.

File /etc/sysconfig/mouse contains mouse settings for service gpm (General Purpose Mouse). This service provides mouse support for console based applications and may be also used by X Window System. After modifying config file, issue /etc/rc.d/init.d/gpm restart if you want the changes to take effect.

File /etc/sysconfig/clock contains clock settings. Its content is used by /etc/rc.d/rc.sysinit script at very early stage of system bootup. This file contains very general clock properties. Setting clock can be done with date and hwclock commands.

Its content is used by rc-scripts at very early stage of system bootup. It contains some basic settings, e.g. system behavior in case of kernel panic, etc.