Linux+ Guide to Linux Certification Chapter Nine System Initialization

Objectives Summarize the major steps necessary to boot a Linux system Configure the LILO boot loader Configure the GRUB boot loader Dual boot Linux with the Windows operating system using LILO, GRUB, and NTLOADER Understand how the init daemon initializes the system at boot time

The Boot Process Power On Self Test (POST) –Initial series of tests run when a computer is powered on to ensure that hardware components are functional Master Boot Record (MBR) –Small program normally located on the first sector of the first hard disk drive used to define partitions and a boot loader Boot loader –Program used to load an operating system

The Boot Process Active partition –Partition that the MBR points to /boot –Directory that contains the kernel and boot- related files Vmlinuz- –The Linux kernel file

The Boot Process Daemon –A Linux system process that provides a certain service Init (initialize) daemon –The first process started by the Linux kernel –It is responsible for starting and stopping other daemons

The Boot Process Figure 9-1: The boot process

Boot Loaders The primary function of boot loaders during the boot process is to load the Linux kernel into memory Boot loaders may perform other functions as well The two most common boot loaders: –LILO –GRUB

LILO Figure 9-2: LILO boot loader screen

LILO /etc/lilo.conf –The LILO configuration file Table 9-1: Common /etc/lilo.conf keywords

LILO Table 9-1 (continued): Common /etc/lilo.conf keywords

LILO

LILO Almost any hardware information may be passed to the kernel via the append= keyword –The format of the information depends on the type of hardware involved To uninstall LILO from an active partition or the MBR, you may use the lilo –u command

LILO Table 9-2: LILO error codes

GRUB GRand Unified Bootloader (GRUB) –Resembles common UNIX boot loaders –More recent than the LILO boot loader –First major part of the GRUB loader typically resides on the MBR –The remaining parts of the boot loader reside in the /boot/grub directory

GRUB Figure 9-3: GRUB boot loader screen

GRUB /boot/grub/grub.conf –The GRUB configuration file GRUB root partition –The partition containing the second stage of the GRUB boot loader and the /boot/grub.conf file

GRUB Normally, GRUB allows users to manipulate the boot loader during system startup –To prevent this, you may optionally password protect GRUB modifications during boot time grub-md5-crypt command –Used to generate an encrypted password for use in the /etc/grub/grub.conf file

GRUB Figure 9-4: GRUB configuration boot loader screen

GRUB Figure 9-5: GRUB prompt boot loader screen

GRUB Figure 9-6: GRUB boot loader help screen

GRUB Recall that you are required to choose a boot loader during installation Grub-install command –Command used to install the GRUB boot loader

Using LILO or GRUB to Dual Boot other Operating Systems Dual boot –Configuration where two or more operating systems exist on the hard disk of a computer If you are using LILO or GRUB to dual boot another operating system in addition to Linux, it is easiest if Linux is installed after the other operating system has been installed

Using LILO or GRUB to Dual Boot other Operating Systems Figure 9-7: Partitioning for a dual boot system

Using LILO or GRUB to Dual Boot other Operating Systems Figure 9-8: Choosing a boot loader for a dual boot system

Using FIPS First non-destructive Interactive Partition Splitter (FIPS) –Program used to create a new partition out of the free space on an existing FAT16 or FAT32 partition –Resizing the Windows partition using FIPS will preserve the Windows operating system on the Windows partition yet allow for free space to install Linux

Using FIPS Guidelines/limitations to using FIPS: –Version 2.0 of FIPS supports the FAT16 and FAT32 filesystems only –FIPS will only work with primary Windows partition and will not resize logical drives within extended partitions –FIPS works by splitting the Windows partition into two primary partition –There must be sufficient free space within the existing Windows to allow for the installation of Linux once the partition for FIPS to use

Using a Windows Boot Loader to Dual Boot Linux NTLOADER –Boot loader available with Windows NT/2000/XP –Can be used to display a screen at boot time that prompts you to choose an operating system to boot –Similar to LILO and GRUB

Using a Windows Boot Loader to Dual Boot Linux Figure 9-9: Configuration screen to put GRUB or LILO to the boot partition

Using a Windows Boot Loader to Dual Boot Linux It is important to create a boot disk when prompted to do so during the installation Boot.ini –The file used to configure NTLOADER

Using a Windows Boot Loader to Dual Boot Linux Figure 9-10: Dual boot operating system choice screen at start up

Linux Initialization Once a boot loader loads the Linux operating system kernel into memory, the kernel resumes control and executes the first daemon process on the system called init /etc/inittab –The configuration file for the init daemon

Runlevels Runlevel –Term that defines a certain type and number of daemons on a Linux system –Since the init daemon is responsible for starting and stopping daemons and hence changing runlevels, runlevels are often called initstates as well

Runlevels Table 9-3: Linux runlevels

Runlevels Table 9-3 (continued): Linux runlevels

Runlevels runlevel command –Command used to display the current and most recent previous runlevel init command –Command used to change the operating system from one runlevel to another telinit command –An alias to the init command

The /etc/inittab File When the init daemon needs to change the runlevel of the system by starting or stopping daemons, it consults the /etc/inittab file /etc/rc.d/rc.sysinit –The first script executed during system startup

The /etc/inittab File Figure 9-11: System startup as a result of /etc/rc.d/rc.sysinit

The /etc/inittab File Figure 9-12: System startup as a result of /etc/rc.d/rc*.d

The /etc/inittab File Mingetty –Program used to display a login prompt on a character-based terminal /etc/rc.d/rc.local –Final script executed during system startup

The /etc/inittab File Figure 9-13: The Linux initialization process

Configuring Daemon Startup /etc/rc.d/rc*.d –The directories used to start and kill daemons in each runlevel /etc/rc.d/init.d –The directory in which most daemons are located

Configuring Daemon Startup Figure 9-14: Results of ntsysv --level 5 command

Chapter 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 The LILO boot loader uses the /etc/lilo.conf configuration file, whereas the GRUB boot loader uses the /boot/grub/grub.conf configuration file You may use the LILO or GRUB boot loader to dual boot Linux and the Windows operating system

Chapter Summary The FIPS utility may be used to split a FAT16 or FAT32 partition in order to create enough space to install Linux There are seven standard runlevels 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 using its configuration file /etc/inittab 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