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Linux+ Guide to Linux Certification, Third Edition. Chapter 8 System Initialization and X Windows. Objectives. Summarize the major steps necessary to boot a Linux system Configure the LILO and GRUB boot loaders

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linux guide to linux certification third edition

Linux+ Guide to Linux Certification, Third Edition

Chapter 8

System Initialization and X Windows

objectives
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

objectives continued
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

the boot process
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

the boot process continued
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

the boot process continued1
The Boot Process (continued)

Figure 8-1: The boot process

Linux+ Guide to Linux Certification, 3e

boot loaders
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

slide8
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

grub continued
GRUB (continued)

Figure 8-2: GRUB boot loader screen

Linux+ Guide to Linux Certification, 3e

grub continued1
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

grub continued2
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

grub continued3
GRUB (continued)

Figure 8-5: Viewing help at the GRUB prompt

Linux+ Guide to Linux Certification, 3e

slide13
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

lilo continued
LILO (continued)

Table 8-1: Common /etc/lilo.conf keywords

Linux+ Guide to Linux Certification, 3e

lilo continued1
LILO (continued)

Table 8-2: LILO error messages

Linux+ Guide to Linux Certification, 3e

lilo continued2
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

dual booting linux
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

using grub or lilo to dual boot other operating systems
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

using grub or lilo to dual boot other operating systems continued
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

using a windows boot loader to dual boot linux
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

Linux+ Guide to Linux Certification, 3e

using a windows boot loader to dual boot linux continued
Using a Windows Boot Loader to Dual Boot Linux (continued)

Figure 8-9: The EasyBCD program

Linux+ Guide to Linux Certification, 3e

using a windows boot loader to dual boot linux continued1
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

linux initialization
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

runlevels
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

runlevels continued
Runlevels (continued)

Table 8-3: Linux runlevels

Linux+ Guide to Linux Certification, 3e

the etc inittab file
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

runtime configuration scripts
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

runtime configuration scripts continued
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

runtime configuration scripts continued1
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

runtime configuration scripts continued2
Runtime Configuration Scripts (continued)

Figure 8-11: The Linux initialization process

Linux+ Guide to Linux Certification, 3e

configuring daemon startup
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

configuring daemon startup continued
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

the x windows system linux gui components
The X Windows System: Linux GUI Components

Figure 8-15: Components of the Linux GUI

Linux+ Guide to Linux Certification, 3e

x windows
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

windows managers and desktop environments
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

windows managers and desktop environments continued
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

windows managers and desktop environments continued1
Windows Managers and Desktop Environments (continued)

Table 8-4: Common window managers

Linux+ Guide to Linux Certification, 3e

windows managers and desktop environments continued2
Windows Managers and Desktop Environments (continued)

Figure 8-16: The KDE desktop environment

Linux+ Guide to Linux Certification, 3e

windows managers and desktop environments continued3
Windows Managers and Desktop Environments (continued)

Figure 8-17: The GNOME desktop environment

Linux+ Guide to Linux Certification, 3e

starting and stopping x windows
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

starting and stopping x windows continued
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

configuring x windows
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

configuring x windows continued
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

configuring x windows continued1
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

configuring x windows continued2
Configuring X Windows (continued)

Figure 8-21: Selecting a keyboard layout

Linux+ Guide to Linux Certification, 3e

configuring x windows continued3
Configuring X Windows (continued)

Figure 8-22: The Display Settings utility

Linux+ Guide to Linux Certification, 3e

configuring x windows continued4
Configuring X Windows (continued)

Figure 8-23: Configuring video card and monitor model

Linux+ Guide to Linux Certification, 3e

configuring x windows continued5
Configuring X Windows (continued)

Figure 8-24: Configuring dual display support

Linux+ Guide to Linux Certification, 3e

configuring x windows continued6
Configuring X Windows (continued)

Figure 8-25: The xvidtune utility

Linux+ Guide to Linux Certification, 3e

summary
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

summary continued
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

summary continued1
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

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