1. Week 8
System Initialization
and X Windows

2. Objectives
 Summarize the major steps necessary
to boot a Linux system
 Configure the LILO and GRUB boot
loaders
 Explain how the init daemon initializes
the system at boot time into different
runlevels
 Configure the system to start daemons
upon entering certain runlevels
Linux+ Guide to Linux Certification, 3e 2

3. Objectives (continued)
 Explain the purpose of the major Linux
GUI components: X Windows, window
manager, and desktop environment
 List common window managers and
desktop environments used in Linux
 Configure X Windows settings
Linux+ Guide to Linux Certification, 3e 3

4. The Boot Process
 POST (Power On Self Test): series of tests
run when computer initializes
Ensures functionality of hardware
 MBR: defines partitions and boot loader
Normally located on first HDD sector
 Boot loader: program used to load an OS
 MBR might contain pointer to a partition
containing a boot loader on the first sector
 Active partition: partition pointed to by MBR
One per HDD
Linux+ Guide to Linux Certification, 3e 4

5. The Boot Process (continued)
 /boot: directory containing kernel and
boot-related files
 Vmlinuz-<kernel version>: Linux kernel
file
 Daemon: system process that performs
useful tasks
e.g., printing, scheduling, OS maintenance
 Init (initialize) daemon: first process
started by Linux kernel
Loads all other daemons
Brings system to usable state
Linux+ Guide to Linux Certification, 3e 5

6. The Boot Process (continued)
Figure 8-1: The boot process
Linux+ Guide to Linux Certification, 3e 6

7. Boot Loaders
 Primary function: load Linux kernel into
memory
 Other functions:
Passing information to kernel during startup
Booting another OS: known as dual booting
 Two most common boot loaders:
GRand Unified Boot loader (GRUB)
Linux Loader (LILO)
Linux+ Guide to Linux Certification, 3e 7

8. GRUB
 More common boot loader for modern
Linux
 Stage1: first major part of GRUB
Typically resides on MBR
Points to Stage1.5
 Stage1.5: loads filesystem support and
Stage2
Resides in /boot/grub
 Stage2: performs boot loader functions
Displays graphical boot loader screen
Resides in /boot/grub
Linux+ Guide to Linux Certification, 3e 8

9. GRUB (continued)
Figure 8-2: GRUB boot loader screen
Linux+ Guide to Linux Certification, 3e 9

10. GRUB (continued)
 To configure, edit /boot/grub/grub.conf
Read directly by Stage2 boot loader
HDDs and partitions identified by numbers
○ Format: (hd<drive#>,<partition#>)
 GRUB root partition: partition containing
Stage2 boot loader and grub.conf file
 GRUB normally allows manipulation of boot
loader
To prevent, enable password protection
 grub-md5-crypt command: generates
encrypted password for use in grub.conf
file
Linux+ Guide to Linux Certification, 3e 10

11. GRUB (continued)
 If press any key during first five seconds after
the BIOS POST get graphical GRUB boot
menu
Manipulate the boot process
Get a grub> prompt to enter commands
○ Help screen provides list of all available commands
 grub-install command: installs GRUB
boot loader
Typically for reinstallation when GRUB becomes
damaged
Linux+ Guide to Linux Certification, 3e 11

12. GRUB (continued)
Figure 8-5: Viewing help at the GRUB prompt
Linux+ Guide to Linux Certification, 3e 12

13. LILO
 Stands for Linux Loader
 Traditional Linux boot loader
No longer supported by Fedora
 Typically located on MBR
 Lilo boot: prompt appears following
BIOS POST
Allows choice of OS to load at startup
 To configure, edit /etc/lilo.conf file
Linux+ Guide to Linux Certification, 3e 13

14. LILO (continued)
Table 8-1: Common /etc/lilo.conf keywords
Linux+ Guide to Linux Certification, 3e 14

15. LILO (continued)
 append= keyword (in /etc/lilo.conf):
Useful for manually passing information
to Linux kernel
Can pass almost any hardware information
○ Format is hardware dependent
 Must reinstall LILO if /etc/lilo.conf file
altered
 lilo command: Reinstalls LILO
-u option: Uninstall LILO
Linux+ Guide to Linux Certification, 3e 15

16. Dual Booting Linux
 Normally only one OS may be used at a
time
Can use virtualization software to run
multiple OSs at the same time
 Dual booting: configuration of boot
loader which allows choice of OS at boot
time
Linux+ Guide to Linux Certification, 3e 16

17. Using GRUB or LILO to Dual Boot
Other Operating Systems
 Easiest if Linux installed after another OS
Allows installation program to detect other OS
○ Place appropriate entries in boot loader
configuration file
 GRUB and LILO cannot load Windows
Kernel directly
GRUB loads Windows boot loader from
Windows partition
LILO uses other= keyword to load boot loader
in appropriate partition
Linux+ Guide to Linux Certification, 3e 17

18. Using GRUB or LILO to Dual Boot
Other Operating Systems
(continued)
Figure 8-7: Configuring GRUB for a dual boot system
Linux+ Guide to Linux Certification, 3e 18

19. Using a Windows Boot Loader to
Dual Boot Linux
 Use EasyBCD to add components to
Windows boot loader
Within EasyBCD, use NeoGrub tab to modify
Windows boot loader to include Linux support
Copy contents of grub.conf into C:NSTmenu.lst
 At next boot, Windows boot loader will
prompt to choose between Windows and
starting the NeoGrub loader to load the
Linux OS
Linux+ Guide to Linux Certification, 3e 19

20. Using a Windows Boot Loader to
Dual Boot Linux (continued)
Figure 8-9: The EasyBCD program
Linux+ Guide to Linux Certification, 3e 20

21. Using a Windows Boot Loader to
Dual Boot Linux (continued)
Figure 8-10: Booting Linux from a Windows boot loader
Linux+ Guide to Linux Certification, 3e 21

22. Linux Initialization
 Kernel assumes control after Linux
loaded
Executes first daemon process (init
daemon)
 /etc/inittab: configuration file for init
daemon
Used to determine number of daemons to
be loaded
 init daemon responsible for unloading
daemons when the system is halted or
rebooted
Linux+ Guide to Linux Certification, 3e 22

23. Runlevels
 Runlevel: defines number and type of
daemons loaded into memory and
executed
init daemon responsible for changing runlevels
○ Often called initstates
Seven standard runlevels
 runlevel command: displays current and
most recent runlevel
 init command: change OS runlevel
telinit command: Alias to init command
Linux+ Guide to Linux Certification, 3e 23

24. Runlevels (continued)
Table 8-3: Linux runlevels
Linux+ Guide to Linux Certification, 3e 24

25. The /etc/inittab File
 Indicates default runlevel which the init
daemon enters
Syntax: id:5:initdefault:
 Contains single uncommented line and
series of explanatory comments
Linux+ Guide to Linux Certification, 3e 25

26. Runtime Configuration Scripts
 Runtime configuration (rc) scripts: scripts
that prepare the system, start daemons
and bring system to usable state
Executed by init daemon
 At boot time, run
/etc/rc.d/rc.sysinit script
Initialize the hardware components, set
variables, check filesystems, and perform
system tasks
 dmesg command: shows output of
hardware detection and
/etc/rc.d/rc.sysinit script
Linux+ Guide to Linux Certification, 3e 26

27. Runtime Configuration Scripts
(continued)
 init daemon executes script for default
runlevel (5) /etc/rc.d/rc5 script
Executes all files that start with S or K in
the /etc/rc.d/rc5.d directory
○ Each file is symbolic link to script for starting or
stopping daemon
○ S/K indicate Start/Kill daemon upon entering
the runlevel
 When user specifies runlevel1, init
daemon runs default script but executes
files in the /etc/rc.d/rc1.d directory
Linux+ Guide to Linux Certification, 3e 27

28. Runtime Configuration Scripts
(continued)
 Message during system initialization
indicates whether each runtime
configuration script has loaded
successfully
Hidden by graphical boot screen display
○ Use Esc key to remove the graphical screen
 Output of runtime configuration scripts is
logged to the /var/log/messages file
Linux+ Guide to Linux Certification, 3e 28

29. Runtime Configuration Scripts
(continued)
Figure 8-11: The Linux initialization process
Linux+ Guide to Linux Certification, 3e 29

30. Configuring Daemon Startup
 Most daemons started by init daemon from
symbolic links in /etc/rc.d/rc*.d directories
Point to daemon executable files in
/etc/rc.d/init.d
 Most daemons accept arguments start,
stop, restart
Can be used to manipulate daemons after system
startup
 service command: start, stop, or restart
daemons within /etc/rc.d/init.d directory
Linux+ Guide to Linux Certification, 3e 30

31. Configuring Daemon Startup
(continued)
 To add daemons to be automatically
started:
Add executable to /etc/rc.d/init.d
Create appropriate links to /etc/rc.d/rc*.d
 chkconfig command: view and modify
daemons that are started in each runlevel
 ntsysv utility: modifies file entries in
/etc/rc.d/rc*.d directories
 Service Configuration utility: easiest way to
control daemon startup by runlevel
Linux+ Guide to Linux Certification, 3e 31

32. The X Windows System: Linux GUI
Components
Figure 8-15: Components of the Linux GUI
Linux+ Guide to Linux Certification, 3e 32

33. X Windows
 X Windows: core component of Linux GUI
Provides ability to draw graphical images in
windows that are displayed on terminal screen
Sometimes referred to as X server
 X client: programs that tell X Windows how
to draw the graphics and display the results
Need not run on same computer as X Windows
 XFree86: OSS version of X Windows
Originally intended for Intel x86 platform
Linux+ Guide to Linux Certification, 3e 33

34. Windows Managers and Desktop
Environments
 Window manager: modifies look and feel
of X Windows
 Desktop environment: standard set of
GUI tools
Works with a window manager to provide
standard GUI environment
Provides toolkits that speed up process of
creating new software
KDE and GNOME are most common
Linux+ Guide to Linux Certification, 3e 34

35. Windows Managers and Desktop
Environments (continued)
 K Windows Manager (kwm): window
manager that works under KDE
 Qt toolkit: software toolkit used with KDE
 GNOME desktop environment: default
desktop environment in Fedora Linux
Metacity window manager
GTK+ toolkit
 Can configure KDE or GNOME to use
different window manager
e.g., compiz
Linux+ Guide to Linux Certification, 3e 35

36. Windows Managers and Desktop
Environments (continued)
Figure 8-16: The KDE desktop environment
Linux+ Guide to Linux Certification, 3e 36

37. Windows Managers and Desktop
Environments (continued)
Figure 8-17: The GNOME desktop environment
Linux+ Guide to Linux Certification, 3e 37

38. Starting and Stopping X Windows
 Runlevel 5 starts GNOME Display Manager
(GDM)
Displays graphical login screen
Allows user to choose the desktop environment
 .dmrc file: contains desktop environments
that were manually selected in a session
menu
By default, root user is not allowed to log into
system using GDM
○ To change this, edit /etc/pam.d/gdm and
/etc/pam.d/gdm-password files
Linux+ Guide to Linux Certification, 3e 38

39. Starting and Stopping X Windows
(continued)
 For runlevel 3:
Start gdm manually, or
Use startx command
 startx command: start X Windows and
Window Manager or desktop
environment specified in .xinitrc file
in home directory
Usually points to .Xclients-default file
Linux+ Guide to Linux Certification, 3e 39

40. Configuring X Windows
 X Windows interfaces with video
hardware
Requires information regarding keyboard,
mouse, monitor, and video adapter card
 Attempts to automatically detect
required information
If automatic detection fails, user needs to
specify correct hardware information
manually
Linux+ Guide to Linux Certification, 3e 40

41. Configuring X Windows
(continued)
 Mouse, keyboard, monitor, and video
adapter card information stored in a file
/etc/X11/xorg.conf file for X.org
implementation of X Windows
/etc/X11/XF86Config file for XFree86
implementation of X Windows
Files can be edited manually or using a
program
 mouse-test command: detect mouse
Should be run as root user
Linux+ Guide to Linux Certification, 3e 41

42. Configuring X Windows
(continued)
 system-config-keyboard
command: start the Keyboard tool in
order to configure keyboard
 system-config-display command:
start the Display Settings utility to
configure video adapter card
 xvidtune utility: fine-tune the vsync and
hsync of the video card and monitor
Linux+ Guide to Linux Certification, 3e 42

43. Configuring X Windows
(continued)
Figure 8-21: Selecting a keyboard layout
Linux+ Guide to Linux Certification, 3e 43

44. Configuring X Windows
(continued)
Figure 8-22: The Display Settings utility
Linux+ Guide to Linux Certification, 3e 44

45. Configuring X Windows
(continued)
Figure 8-23: Configuring video card and monitor model
Linux+ Guide to Linux Certification, 3e 45

46. Configuring X Windows
(continued)
Figure 8-24: Configuring dual display support
Linux+ Guide to Linux Certification, 3e 46

47. Configuring X Windows
(continued)
Figure 8-25: The xvidtune utility
Linux+ Guide to Linux Certification, 3e 47

48. Summary
 Boot loaders are typically loaded by the
system BIOS from the MBR or the first
sector of the active partition of a hard disk
 The boot loader is responsible for loading
the Linux kernel and to boot other OSs in a
dual boot configuration
 The GRUB boot loader uses the
/boot/grub/grub.conf configuration file and
the LILO boot loader uses the /etc/lilo.conf
configuration file
Linux+ Guide to Linux Certification, 3e 48

49. Summary (continued)
 Seven standard runlevels are used to
categorize a Linux system based on the
number and type of daemons loaded in
memory
 The init daemon is responsible for loading
and unloading daemons when switching
between runlevels
 Daemons are typically stored in the
/etc/rc.d/init.d directory and loaded at
system startup from entries in the
/etc/rc.d/rc*.d directories
Linux+ Guide to Linux Certification, 3e 49

50. Summary (continued)
 The Linux GUI has several interchangeable
components: X server, X clients, Window
Manager, and optional desktop environment
 X Windows is the core component of the Linux
GUI that draws graphics to the terminal screen
 You can start the Linux GUI from runlevel 3 by
typing startx at a command prompt, or from
runlevel 5 by using the gdm
 The hardware information required by X
windows is automatically detected, but can be
modified
Linux+ Guide to Linux Certification, 3e 50