topic 1 - intro to linux

7/23/2019 Topic 1 - Intro to Linux

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Introduction to Linux


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t oduct o to u

nstructors info

Instructor : NGUYEN PHUONG QUAN

Mobi : 0972.259.260

Email : [email protected]

Com : SHB


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Linux Professional Institute Certification

Junior Level Administration (LPIC-1) Work at the command line.

Perform basic maintenance tasks.

Install and configure a workstation

Advanced Level Administration (LPIC-2) Administer a small to medium-sized site containing

Microsoft and Linux servers.

Supervise assistants.

Advise upper manangement.

Senior Level Administration (LPIC-3)


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Histoy of LINUX, UNIX

1983: GNU

1985: GPL

1991: Linux

1994: Redhat

2001: Linux 2.4Linus Torvald Tux


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LINUX VS UNIX

Linux Unix


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Linux Installation

2. Linux Boot Process

1. Linux Installation


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Linux Installation


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File System Overview

Linux filesystem is a single tree with the /directory as its root directory.

You create the single tree view of the

filesystem by mounting the filesystems ondifferent devices at a point in the tree called

a mount point

Files or subdirectories that were already inmountpoint are no longer visible when new

filesystem is mounted there


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Filesystem Hierarchy Standard


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Partitions

Three types of partition on hard

drives:primary,logical, andextended

Thepartition table is located in themaster boot

record (MBR) of a disk

When more than 4 partitions are required, one oftheprimarypartitions must become an extended

partition

Linux numbers primary or extended partitions as 1through 4

If logical partitions are defined, they are

numbered starting at 5


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Recommended Partition Scheme

Mountpoint Size Description

/ 4GB or

more

Contains all directories not

present on other filesystems

swap 2 x RAM size used to support virtual memory

/boot 100MB Contains the Linux kernel and

boot files

/home 200MB per

user

Default location for user home

directories

/var 2GB or

more

Contains log files and spools

/tmp As much as

possible

Holds temporary files created by

programs


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Linux Installation Process

1. Boot from an installation source

2. Select installation mode

3. Select language and keyboard layout

4. Partition the hard disk

5. Select boot loader options

6. Configure network interfaces

7. Select time zone

8. Set roots password

9. Customize software packages to be installed

10. Start the installation


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Linux Boot Process


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Boot Loader PrinciplesLinux

1. Boot process begins with the BIOS2. BIOS load the MBR (primary boot loadercode)

3. Primary boot loadereither:

A. Loads the boot sector from bootable primary partition

(secondary boot loader), which continues the process byloading an OS kernel. DOS and Windows use this.

B. Load the OS kernel directly (bypass the secondary bootloader). Linux supports this.


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Linux boot loader

LILO (LInuxLOader) or GRUB (GRandUnifiedBootloader)

Can be installed in MBR or boot sector of primarybootable partition.

Trouble comes if your system is dual-boot (Windows+ Linux) Install LILO/GRUB in MBR: can be wiped out if you re-installing

Windows

Install LILO/GRUB in boot sector: remain intact, although Windowsmight configure the system to bypass it.

This partition must be a primary partion

You must you FDISK to re-mark the Linux partition as the boot partitoin


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LILO vs GRUB

LILO GRUB

Configuration file /etc/lilo.conf /boot/grub/grub.confor

/boot/grub/menu.lst

Support booting from a

network

No Yes

Command to install lilo grub-install

Require re-install after

changing configuration file

Yes No


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Example of grub.conf


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Example of lilo.conf


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Linux boot process

System booting process:

1. System is power on, CPU runs the BIOS

2. BIOS load the primary boot loader in MBR

3. Primary boot loader load secondary loader in boot sector

4. Boot loader load the Linux kernel

5. Linux kernel initializing devices, mounting root partitionand run /sbin/init

6. /sbin/init read /etc/inittab to determine what otherprogram to run based on default runlevel

Extracting information about the boot process:dmesg | lessless /var/log/messages


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Runlevel


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The System Startup Scripts

Runlevel specific scripts are stored in /etc/rc.d/rc?.dor /etc/init.d/rc?.d

All scriptss name are begin with S or K Example: S10network, K35smb

Scripts are actually symbolic links to main scripts in/etc/rc.d or /etc/init.d/

When entering a runlevel, rc:

pass start parameter to S* scripts

pass stop parameter to K* scripts


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Managing Runlevel

View default runlevel

grep :initdefault: /etc/inittabView current runlevel:runlevel

Change to another runlevel:

telinit runlevelList the services and their applicable runlevels:chkconfig --list [servicename]

Modify the runlevels in which a services run

chkconfig --level runlevels servicename {on|off|reset} Example:chkconfig --level 345 nfs-common on

Text-based menu driven tools:ntsysv


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Exercise

1. Login as root in graphical mode

2. Learn your current runlevel with runlevel

3. If your system reports its in runlevel 5, type telinit 3 to switchto runlevel 3. See whats difference?

4. Return to your orginal runlevel with telinit 5

5. Edit /etc/inittab and change the default runlevel to 3

6. Reboot the computer by typing reboot now or shutdown -rnow

7. Login as root again and type runlevel to verify that yourerunning in the runlevel you specified in step 5

8. Edit /etc/inittab to restore it to its original state

9. Type telinit 6. This enters runlevel 6, which reboot the system.


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Q A

Thank You

topic 1 - intro to linux

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