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Linux+ Guide to Linux Certification, Third Edition Chapter 8 System Initialization and X Windows.

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Presentation on theme: "Linux+ Guide to Linux Certification, Third Edition Chapter 8 System Initialization and X Windows."— Presentation transcript:

1 Linux+ Guide to Linux Certification, Third Edition Chapter 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, 3e2

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, 3e3

4 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

5 Linux+ Guide to Linux Certification, 3e5 The Boot Process (continued) /boot: directory containing kernel and boot-related files Vmlinuz- : 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

6 Linux+ Guide to Linux Certification, 3e6 The Boot Process (continued) Figure 8-1: The boot process

7 Linux+ Guide to Linux Certification, 3e7 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)

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, 3e8

9 GRUB (continued) Linux+ Guide to Linux Certification, 3e9 Figure 8-2: GRUB boot loader screen

10 GRUB (continued) To configure, edit /boot/grub/grub.conf –Read directly by Stage2 boot loader –HDDs and partitions identified by numbers Format: (hd, ) 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, 3e10

11 Linux+ Guide to Linux Certification, 3e11 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

12 Linux+ Guide to Linux Certification, 3e12 GRUB (continued) Figure 8-5: Viewing help at the GRUB prompt

13 Linux+ Guide to Linux Certification, 3e13 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

14 Linux+ Guide to Linux Certification, 3e14 LILO (continued) Table 8-1: Common /etc/lilo.conf keywords

15 Linux+ Guide to Linux Certification, 3e15 LILO (continued) Table 8-2: LILO error messages

16 Linux+ Guide to Linux Certification, 3e16 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

17 Linux+ Guide to Linux Certification, 3e17 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

18 Linux+ Guide to Linux Certification, 3e18 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

19 Linux+ Guide to Linux Certification, 3e19 Using GRUB or LILO to Dual Boot Other Operating Systems (continued) Figure 8-7: Configuring GRUB for a dual boot system

20 Linux+ Guide to Linux Certification, 3e20 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:\NST\menu.lst At next boot, Windows boot loader will prompt to choose between Windows and starting the NeoGrub loader to load the Linux OS

21 Linux+ Guide to Linux Certification, 3e21 Using a Windows Boot Loader to Dual Boot Linux (continued) Figure 8-9: The EasyBCD program

22 Linux+ Guide to Linux Certification, 3e22 Using a Windows Boot Loader to Dual Boot Linux (continued) Figure 8-10: Booting Linux from a Windows boot loader

23 Linux+ Guide to Linux Certification, 3e23 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

24 Linux+ Guide to Linux Certification, 3e24 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

25 Runlevels (continued) Linux+ Guide to Linux Certification, 3e25 Table 8-3: Linux runlevels

26 Linux+ Guide to Linux Certification, 3e26 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

27 Linux+ Guide to Linux Certification, 3e27 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

28 Linux+ Guide to Linux Certification, 3e28 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

29 Linux+ Guide to Linux Certification, 3e29 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

30 Linux+ Guide to Linux Certification, 3e30 Runtime Configuration Scripts (continued) Figure 8-11: The Linux initialization process

31 Linux+ Guide to Linux Certification, 3e31 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

32 Linux+ Guide to Linux Certification, 3e32 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

33 Linux+ Guide to Linux Certification, 3e33 The X Windows System: Linux GUI Components Figure 8-15: Components of the Linux GUI

34 Linux+ Guide to Linux Certification, 3e34 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

35 Linux+ Guide to Linux Certification, 3e35 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

36 Linux+ Guide to Linux Certification, 3e36 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

37 Linux+ Guide to Linux Certification, 3e37 Windows Managers and Desktop Environments (continued) Table 8-4: Common window managers

38 Linux+ Guide to Linux Certification, 3e38 Windows Managers and Desktop Environments (continued) Figure 8-16: The KDE desktop environment

39 Linux+ Guide to Linux Certification, 3e39 Windows Managers and Desktop Environments (continued) Figure 8-17: The GNOME desktop environment

40 Linux+ Guide to Linux Certification, 3e40 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

41 Linux+ Guide to Linux Certification, 3e41 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

42 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, 3e42

43 Linux+ Guide to Linux Certification, 3e43 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

44 Linux+ Guide to Linux Certification, 3e44 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

45 Linux+ Guide to Linux Certification, 3e45 Configuring X Windows (continued) Figure 8-21: Selecting a keyboard layout

46 Linux+ Guide to Linux Certification, 3e46 Configuring X Windows (continued) Figure 8-22: The Display Settings utility

47 Linux+ Guide to Linux Certification, 3e47 Configuring X Windows (continued) Figure 8-23: Configuring video card and monitor model

48 Linux+ Guide to Linux Certification, 3e48 Configuring X Windows (continued) Figure 8-24: Configuring dual display support

49 Linux+ Guide to Linux Certification, 3e49 Configuring X Windows (continued) Figure 8-25: The xvidtune utility

50 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, 3e50

51 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, 3e51

52 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, 3e52


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