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index

Units:

unit-1 About the founder of Linux.unit-2 Linux VS Windows.

unit-3 Linux Flavors.

unit-4 Introduction to Redhat Linux.

unit-5 Kernel.

unit-6 Types of shells

unit-7 Dos Vs Linux.

unit-8 Redhat Linux Installationunit-9 Hardware Requirements

unit-10 Installation Methods



Unit -1

http://www.cs.helsinki.fi/u/torvalds/linux_logo.gif



About the founder of LINUX

•Linus Benedict Torvalds (bornDecember 28, 1969) began the

development of Linux, an operatingsystem kernel, and today acts as theproject coordinator.

•Inspired by Minix (a kernel andoperating system developed by AndrewTanenbaum), he felt the need for acapable UNIX operating system that hecould run on his home PC.

•Torvalds did the original developmentof the Linux kernel primarily in his owntime and on his equipment.



•Torvalds originally used Minix on hiscomputer, a simplified kernel written

by Andrew Tanenbaum for teachingoperating system design.

•The Linux system quickly surpassedMinix in functionality.

•The first version of the Linux kernel

was released to the Internet inSeptember 1991. with the secondversion following shortly thereafter inOctober

Evolution of Linux



•Penguin is the official mascot of the Linux operating system.

•Tux, is a chubby penguin that

looks content and satisfied.

•The concept of the Linux mascotbeing a penguin came from LinusTorvalds, the creator of the Linuxkernel.

TUX - the penguin



GNU’s (Not Unix)

• The GNU project was started in 1983 for developing a completeUnix-like operating system, including software development

tools and user application programs, entirely of free software.

• By the release of the first version of the Linux kernel, the GNU

project had produced all the necessary components of this

system except the kernel.

• Torvalds and other early Linux-kernel developers adapted their

kernel to work with the GNU components and user space

programs to create a fully functional operating system.



FEATURES OF LINUX

• Open source development model.

• Supports wide variety of hardware.

• Supports many networking protocols and configurations

• Supports more File systems.

• Linux has a reputation for fewer bugs (programming

mistakes) than Windows.



Linux Vs Windows

Open Source Development Modeland so the programmer can redesignthe OS.

It is not an open source and hencecannot be redesigned by theprogrammer.

Linux is robust and very much securefrom virus.

Windows gets affected by virus veryeasily.

The Linux servers has surpassedwindows server operating system insecurity.

Security is the main issue which hasmade windows to think to survive.

It costs less to design and implementa Linux Network.

It costs more to implement WindowsNetwork administration, whencompared to Linux.

There are 250000+ developers behindLinux for open source deployment.

Compared to Linux, windows isdeveloped by few thousands of people.

http://www.cs.helsinki.fi/u/torvalds/linux_logo.gif



Linux Flavors

• Red Hat Linux (Red Hat)

• Fedora Linux

• Open Linux (Caldera)

• SuSE Linux (Novell)

• Mandrake Linux (Mandrake)

• Turbo Linux (Pacific Hi-Tech)

• Linux PPC (MAC Power PC version)

• Info magic

• Slack ware Linux Project

• Knoppix (Live CD) etc.,



Introduction to Red Hat Linux

• Red Hat has split its Linux development into two lines :

• Red Hat Enterprise Linux and

• The Fedora Project.

• Red Hat EL features commercial enterprise products

for servers and workstations, with controlled releases

issued every two years.

• The Fedora project is an open source initiative whose

Fedora Core release will be issued every six months.



Kernel

• The kernel is the essential center of a computer operating system, the core that provides basic services

for all other parts of the operating system.

• A kernel can be contrasted (compared) with a shell,shell is the outermost part of an operating system thatinteracts with user commands.

• Kernel and shell are terms used more frequently in Unixoperating systems than in IBM mainframe or MicrosoftWindows systems.



• Bash shell (Bourne again Shell)

– Developed for the GNU Project

– The actual standard Linux shell

– Default shell for Red Hat Linux

• Borne shell (sh) – Original Unix shell written by Bill

Joy at UC Berkeley

• C shell (csh)

– Added many features such as command, history

and job control

Continue…

Shells



• Korn Shell (Ksh) – Written by David Korn

• Implemented many csh features such as command

completion and history

• The Enhanced C shell (tcsh) –a community effort

• More features like command-line editing and more

sophisticated completion

Shells



command

prompt for bash

shell

Type bash and

hit enter

Shells



command

prompt for c-

shell (csh)

Shells



command prompt

for enhanced C

shell (tcsh)

Shells



command

prompt for

bourne shell(sh)

Shells



commandprompt for korne

shell (ksh)

Shells



DOS Vs LinuxDOS

Command

LINUX Command Action

DIR ls -l List directory contents

TREE ls –R List directory

recursively

CD cd Change directory

MKDIR mkdir Make a new directory

RMDIR rmdir Remove a directory

CHDIR pwd Display directory

location

DEL rm Remove a file



DOS Command LINUXCommand

Action

RMDIR /S (NT)DELTREE (Win95...)

rm -r Remove all directories and files belowgiven directory

COPY cp Copy a file

XCOPY cp -r Copy all file of directory recursively

RENAME or MOVE

mv Rename/move a file

TYPE cat Dump contents of a file to users screen

MORE more Pipe output a single page at a time

HELP or COMMAND /?

man Online manuals

DOS Vs Linux



DOSCommand

LINUXCommand

Action

CLS clear Clear screen

EXIT exit Exit a shell

FIND find Look for a word in files given in command line

FC diff Compare two files and show differences. Also seemgdiff and tkdiff.

SET set and env Show environment variables

ECHO text echo text Echo text to screen

DOS Vs Linux



DOSCommand

LINIUX Command Action

SETvariable export variable name Set environment variables

PATH echo $PATH Display search path for executables

DATE or TIME

date Show date. (also set date -DOS only)

SORT sort Sort dataalphabetically/numerically

EDITfilename.txt vim

Edit a file. The Linux editor which looks most like DOSedit is probably Pico.

\ / Directory path delimiter

.\ ./ Current directory

..\ ../ Parent directory

DOS Vs Linux



DOS Command LINUX Command Action

BACKUP files A:\ tar -cvf /dev/fd0files

Save backup files to floppy

RESTORE A:\ filestar -xvf /dev/fd0files

Read files from floppy.See Using DOS floppies

ATTRIB +h or -h mv file .file Change file to a hidden file - renamefile with prefix "."

PRINT lpr Print a file

MEMfreetop

Show free memory on system

MSD lsdevShow system info (Commandborrowed from AIX)

DOS Vs Linux




SCANDISKDEFRAG C:

fsck Check and repair hard drive file system

FDISK fdisk Tool to partition a hard drive.

FORMATmke2fsSee: fdformat for floppy

Format drive file system.For floppy drive use see YoLinux TutorialUsing DOS Floppies with Linux

VER uname -a Operating system version

pkziptar, gzip andbzip2

Compress and uncompressfiles/directories. Use tar to create Linuxalso has compress, gzip

HOSTNAME hostname Print host name of computer

DOS Vs Linux



DOS CommandLINUXCommand

Action

PING ping Send packets to a network host

TRACERT tracerouteShow routes and router hops togiven network destination.

IPCONFIG (NT)WINIPCFG (Win 95...)

ifconfig Display/configure network interface

NBTSTAT (Netbios info:

-n, -c)NBTSTAT -a host-name NBTSTAT -A IP-address

nslookup host-name Print DNS info for host.

ROUTE PRINT route -n Print routing table.

DOS Vs Linux



DOS CommandLINUXCommand

Action





NBTSTAT (Netbios info:-n, -c)

NBTSTAT -a host-name NBTSTAT -A IP-address

nslookup host-

namePrint DNS info for host.


Network Commands



Hardware Requirement

32-bit Intel based processor, atleast an Intel or compatible 80386,

80486, or Pentium-classmicroprocessor is required.

400 MHz Pentium is recommendedfor a graphical interface and 200

MHz for text.

Normally 64MB RAM for Text, and192 MB for graphical. (Linux canrun on as little as 12 MB RAM).

At least 2GB free hard disk spacefor a standard installation, includingapplications; 3 to 6 GB or more isrecommended for a full installation(all applications).



Installation Methods

Red Hat Installation CD-ROM.

NFS Image.

Kick Start

FTP

HTTP



• To boot from a CD-Rom or DVD-Rom, you may first

have to change the boot sequence setting in your

computer’s BIOS so that the computer will try to boot

first from the CD-Rom.

Red Hat Installation through CD



NFS Image

• NFS (Network File Sharing): It is a common method

to share files.

• An image of an operating system is taken already

which is connected remotely to install the image in a

system.

• The image system is first mounted and operating

system path is given to get into the installation.



Kick Start Installation

• Till now we have seen attended installation, where the user have to interact with the system.

• The kick start installation is known as unattended

installation where the user appearance is not necessary.• The system will automatically install the operating system

into the machine including the device installation, hard disk

partition, assigning of ip address etc.,



Red Hat Installation

Press Enter, toinstall in

Graphical mode.



Type linuxtext, to installin Text mode.




Type linux askto install either tFTP, HTTP, Ha

and NFS.





Type linux textaskmethod to installeither through FTP,

HTTP, Hard disk andNFS.



Installation Setup Screen

Type Linux Text and

press enter for Text

mode Installation

The InstallationMode is selected here

Just press enter

for graphical

mode Installation.



Hardwaredetection

process

Hardware Detection



Select theInstallationlanguage.

R dh t I t ll ti



Redhat Installations

Select the typeof keyboard

layout.

R dh t I t ll ti



Select theappropriate

type of

installation.


R dh t I t ll ti



Select theappropriateNFS type

installation.


R dh t I t ll ti



Select thisoption to assignan dynamic ip

address.





Enter theappropriate ip

address





Enter theinformation of

server ip addressand directory.





The Anaconda-Red Hat

Installer begins

the Installation.





Hardwaredetection

process





The Red Hat LinuxWelcomes

you.


S l h P i i i T



Select the Partitioning Type

Select this for simpler automatic

partitioning.

Click here for manualpartitioning. Raid and LVM

also can be configured(Disk Druid tool can be

used only while installation)




Click here tocreate new

partition in thefree space


Creating Partition for /boot directory



Enter themount pointshere.( /boot )

Select the file systemtype here.( ext2, ext3for normal partitionand swap for swap

partition)

Enter the sizeof the

partitionshere.

Creating Partition for /boot directory

Creating Partition for / directory



Enter themount points

here.( / )

Select the file systemtype here.( ext2, ext3

for normal partition andswap for swap

partition)


partitions here.

Creating Partition for / directory

Creating Partition for swap directory



Enter themount pointshere.(swap)


partitions here.

Creating Partition for swap directory

R dh I ll i



The final viewall the

mounting

point.




eth0 means firstEthernet card its

address gettingfrom DHCP.

Hostnamealso gettingfrom DHCP

server..


Fi ll C fi tiFi ll C fi ti



Firewall Configuration

No firewall optionallows all networkservices to your

machine

Firewall Configuration

No firewall optionallows all networkservices to your

machine




Enable firewalloption allows

specific networkservices to your

machine

Activate your SELINUX options





Choose thedefault language

for the system.





Time zone isselected here.





Enter the

password for theroot (Super User)





Its readingpackage

information's.





Select customizeoptions to customize

the package selections

This is used to selectthe default package.


Package Selection



Package Selection

The Packages to beinstalled are selectedhere. Even the office

(Like MS-Officein windows)

Packages areavailable inbuilt

in Red Hatinstallation CD

Package Selection



Package Selection

Checking andinstalling thepackages.

Beginning of Installation



Click next to beginthe actual installationwhich begins writing

the operating systemin the hard drives.

Beginning of Installation

Installing Packages



Creating the file

system in theinstallationpartition.

Installing Packages

Installing Packages



The installationimage is copiedto the hard drive.

Installing Packages

Installing Packages



Initializing theinstallation

process

Installing Packages

Installing Packages



Preparing for theinstallation

process

Installing Packages

Installing Packages



Installation of packages under

progress

Installation of tzdata packages

Installing Packages

Installing Packages




progress

Installing Packages

Installing Packages




progress

s a g ac ages




progress

Installing Packages



Installing Packages


progress

Installing Packages




progress

g g

Installing Packages



Performing thepost install

configuration.

Installing Packages

Reboot the System



The Red Hat Installation iscompleted successfully.Remove any Installation

media and boot disks.And reboot the system.

y

Rebooting



g

GRUB boot loader



Highlight the operatingsystem and press enter

to boot.

Loading Kernel



g

Initializing hardware devices



g

Initializing services



g

Welcome to Red Hat Setup



p

The Red Hatsetup agentwill proceed

someMore basic

configurationsBefore the system

is readyto use.

WelcometoRed Hat Linux

Setup agent

License agreement



Setting date and time



Graphics configuration



Select the Colour depth-the number of distinct

colours requiredsupporting the video

card Installed

Select the screen

resolution suiting your monitor and display

card

p g

Red Hat Login



To register the systemto Red Hat enter the

Login name andpassword.

Red Hat Login



If you don’t have redhatlogin select this optionto create a new login.

Red Hat Login



Enter this optionto know the

details

Red Hat Login



Click here toskip registration

Click here toregister with theRed Hat network

The update agentregisters the

machine withRed Hat networkSo that the latest

Software packagesGet updatedautomatically

System user creation.



Create nonadministrative user toaccess the system.

Sound Card Configuration



Sound gettingConfigured

automatically

Tests sounds for the 3channels in sound card

can be heard byselecting play test sound

To Install additional softwares



Click here to install

any additional

software.

Finishing Setup



The Red Hatsetup agent

Finishes the setup

Login Screen



Login Screen



Red Hat supportsmany languages,the language can

be selected beforelogin.

Login Screen



The kind of desktop

can be selectedhere.

Login Screen



The system canbe rebooted using

the option.

Login Screen



The system canbe restarted using

the option.

Login Screen



Enter the user Name

Login Screen



Enter the user Password.

Loading the user settings.



Red Hat Startup Screen



Now the Red Hat

Linuxis ready for use.

Kernel initialization



• As systems boots, kernel get initialized and thefollowing functions are occurred.

• Device detection: kernel will compile the device

drivers and locate it to the corresponding devices.

• Mounts root file system: After the device detectionthe kernel will mount the root file system as readonly.

• Load initial process: The very first process (init) isthen loaded.

Initial process



• Init :

• It is the superior of all processes.

• As soon as init process is loaded the control is

passed from kernel to this process.

• /etc/inittab:

• File which contains the information on how initshould setup the system in every run level, as well

as the run level to use a default.

Run levels



init 0 : Shutdown the system or halt

init 1 : Single-user mode.

init 2 : Multi-user mode with out networking support.

init 3 : Multi-user mode with networking support.

init 4 : Unused.

init 5 : Graphical user interface.

init 6 : Reboot the system.

Run level configuration file



Get in to theinittab file, the

init configurationfile.

Run level configuration file



The defaultrun level canbe changed

here.

CONSOLES



• Text-mode login at virtual console

• Multiple non-GUI logins are possible

• Default consoles are in text mode

• Available through CTRL-ALT-F[1-6]

• Graphical login• Graphical console comes through CTRL-ALT-F7

X Window System



• It is the foundation for the graphical user Interface of

Red Hat Linux.

• X applications communicate with a display via. The X

protocol.

• X is OS Independent.

• It is available on many platforms.

X Protocol



• It hides the individual details of the OS and the underlying hardware.

• X protocol is a asynchronous network protocol for the communication

between X client and X Server.

• It defines how the graphical primitives are communicated between X client

and server.

Multiple Desktop Environments



• The X Window System of Red Hat provides two Desktop

Environments.

• GNOME (GNU Network Object Modules Environment).

• KDE (K desktop Environment).

GNOME



• It is the default desktop environment for Red Hat

Linux.

• It is Power full and easy-to-use desktop environment

consisting primarily of a panel and a set of GUI tools.

• GNOME is free and hence its source code can be

downloaded form the GNOME Web Site:

www.gnome.org.

GNOME Interface



• The GNOME Interface consists of a Panel and a Desktop.

• Panel appears as a long bar across the bottom of screen.

• Panel holds Menus, Programs and Applets.

• The Remainder Screen is the Desktop. Here you can place

directories, files or programs.

GNOME Desktop



GNOME Menus



KDE



• KDE provides an alternative desktop environment with full

set of integrated network and internet applications.

• Along with GNOME features, It also includes

• Konsole : Highly configurable graphical terminal.

• Konqueror : A file manager and web browser.

• Kmail : A graphical email client.

• Kdevelop : Integrated development.

KDE Desktop



KDE Desktop



Starting X Window



The X window start automatically, If so then a

Graphical login screen is prompted by the Display

manager.

Alternatively use startx to get in to X window from

non-windowing console.

Start X



To get in to Xwindow from run

level-3

Start X



Desktop Selection



To get in to the previously used

desktop

Select failsafe

in case of anygraphical

failure

To get the

default

desktop.To get in to

GNOME

desktop.

To get in to

KDE desktop.

KDE MODE



If you click yes theKDE desktop is set

as default desktopfor future sessions(or) login

If you click No, onlythe current sessionis set to KDE.

Switchdesk



To change thedesktop environment.

Switchdesk



To switch from kdeto gnome desktop



Linux File System Directories

Directory Function



/ Begins the file system structure – called the root./boot Hold the kernel image files and associated boot

information and files.

/home Contains user’s home directories.

/sbin Holds administration-level commands and anycommands used by the root user.

/dev Holds file interface for devices such as the terminaland the printer.

/etc Holds system configuration files and any other system files.

/etc/opt Holds system configuration files for application in/opt

y


Directory Function



/etc/X11 Holds system configuration files for the X WindowSystem and its applications.

/bin Holds the essential user commands and utilityprograms.

/lib Holds essential shared libraries and kernel modules.

/lib/modules Holds the kernel modules.

/mnt Used to hold directories for mounting file systems

like CD-ROMs or floppy disks that are mounted onlytemporarily.

/opt Holds added software applications (for example,KDE on some distributions).

y

Directory Function




/proc Process directory, a memory-resident directorycontaining files used to provide information aboutthe system.

/tmp Holds temporary files.

/usr Holds those files and commands used by thesystem; this directory breaks down into severalsubdirectories.

/var Holds files that vary, such as mailbox and FTP files.

y



Linux Commands



• Commands have the following syntax:

• Command [options] [arguments]

• Each item is separated by space

• Options modify the command’s behavior

• Arguments are filenames or other information

needed by the command

• Separate commands with semicolon (;)

DOS Vs LinuxDOS LINUX Command Action



Command

DIR ls -l List directory contents

TREE ls –R List directory recursivly

CD cd Change directory

MKDIR mkdir Make a new directory

RMDIR rmdir Remove a directory

CHDIR pwd Display directory

location

DEL rm Remove a file

DOS Command LINUX Action

DOS Vs Linux



Command

RMDIR /S (NT)

DELTREE (Win95...)

rm -r

Remove all directories and files below

given directory

COPY cp Copy a file

XCOPY cp -r Copy all file of directory recursively

RENAME or MOVE

mv Rename/move a file

TYPE cat Dump contents of a file to users screen

MORE more Pipe output a single page at a time

HELP or COMMAND/?

man Online manuals

DOSCommand

LINUXCommand

Action

DOS Vs Linux



Command Command

CLS clear Clear screen

EXIT exit Exit a shell

FIND grep Look for a word in files given in command line

FC diff Compare two files and show differences. Also seemgdiff and tkdiff.

SET set and env Show environment variables

ECHO text echo text Echo text to screen

DOSCommand

LINIUX Command Action

DOS Vs Linux



Command

SET

variable

export variable nameSet environment variables

PATH echo $PATH Display search path for executables

DATE or TIME

date Show date. (also set date -DOS only)

SORT sort Sort dataalphabetically/numerically

EDITfilename.txt vim

Edit a file. The Linux editor which looks most like DOSedit is probably Pico.

\ / Directory path delimiter

.\ ./ Current directory

..\ ../ Parent directory


DOS Vs Linux



BACKUP files A:\

tar -cvf /dev/fd0

files

Save backup files to floppy

RESTORE A:\ filestar -xvf /dev/fd0files

Read files from floppy.See Using DOS floppies

ATTRIB +h or -h mv file .file Change file to a hidden file - renamefile with prefix "."

PRINT lpr Print a file

MEM freetop Show free memory on system

MSD lsdevShow system info (Commandborrowed from AIX)



DOS CommandLINUXC d

Action

DOS Vs Linux



DOS CommandCommand

Action





NBTSTAT (Netbios info:-n, -c)

NBTSTAT -a host-name NBTSTAT -A IP-address

nslookup host-

name

Print DNS info for host.


DOS Command

LINUXCommand

Action

Network Commands



Command





NBTSTAT (Netbios info:-n, -c)NBTSTAT -a host-name

NBTSTAT -A IP-address

nslookup host-

namePrint DNS info for host.




Login screen



Enter the

user name

PWD



• PWD

• Present working Directory

• Display the absolute path of the current directory.

PWD



The absolute path of the

root directory

is displayed.

lsls :



List the Files and Directories within the current directory.

Syntax:

ls [options]

Options:

-l List file with permission.

-a List hidden file.

-i List files and inode number.

-R List directories , sub directories and their contents.

ls



Lists the files and

directories in the

present directory.

ls -l



l option lists the

long listing of

Files and

directory.

l l command



File or directory

names.

Time stampSize of the filesor directories

The name of the group

which has the

permissions over thefiles or directories

Owner name, the

user who created

the directory.

No of links to the

directory

It defines the

permissions

assigned to the

owners, groups andother users

ls -a



[a] option lists all filesand directories including

hidden files

ls -al



al option lists all files

and directories includinghidden files in long listin

format.

ls -R



[R] option lists working

directory as well as

contents in the directory.

mkdir



mkdir :Make directory (or) To create a directory

Syntax :

mkdir <dirname>

mkdir



This will create adirectory advpro.

cd

cd



cd

- Change directoriesSyntax :

cd <directory name>

cd ..

- To a directory one level up (parent directory)

cd -

- To your previous working directory

cd /

- To the / (slash) directory

cd



This command

will take you to

the directory .

cd ~



Previous slide

we have seen cd

along with any

directory name.

This command

cd ~ <enter>will take to your

home directory

cd ..



cd .. Take you to theparent directory of

the current directory.

cd ..



Now we can see that

we are in advpro

directory, the parent

directory of the test



cd /



Confirmed

through the pwd

command

cd –Here the current

di i di



cd -

command will take

you to the previous

working directory

directory is newdir

when we enter cd -, ittakes to the previously

worked directory.Again cd - is given as

shown. Now it will take

to the previously

worked directory i.e.,(newdir)

catcat



– it is the command to create and view files

Syntax:

• cat [options] [filename]

cat > [filename] To create a file

cat [filename] To view a file

cat >> [filename] To append text to a

file

cat



As mentioned in

the previousslide. cat is used

to create a file

The file is savedthrough ctrl -d

after typing the

text



cat



To append the

text in a file,

Cat >> (symbol)

and file name.

cat



The screen

shows the

appended file

cat



The -s option

trims multiple

adjacent blank

lines into single

blank line

cat



The –b option

numbers the

each text line

of the output

cat



The –A option shows

all characters including

control and non

printing characters

Here the $ represents

the end of the line

touch

touch command is used to update the time stamps of a file.



touch is also used to create empty file.

– Syntax : touch [filename]

touch can create multiple empty file too.

– Syntax : touch [filename1] [filename2]



M lti l fil

touch



Multiple files

are createdusing touch

command



Copy Command



There is a file

named ‘a’ inthe directory

test .

Here we notice that

Copy Command



Here we notice that

test1 is a emptydirectory. Let us

copy the file ‘a’ intothis directory.

C i h fil ‘ ’

Copy Command



Cp copies the file ‘a’

from the directorytest to the directory

test1.

Copy Command



Thus the file ‘a’is copied to thetest1 directory.



Copy Command



-r option copy

the entiredirectory tree‘old’

Copy Command



Thus thecontents of

old directoryis copied to

newdirectory.

Copy Command



Command l lshows the

permission of the file

Copy Command



Using chmod,permission of

the file is

changed



Copy Command

See the



comparisonof the file one shown above

in the new and old

directory

Copy Command



Now using commandcp along with –p option

the permission ispreserved.

mv : This command is used to move and renaming files

Move Command



mv : This command is used to move and renaming files

and directories

Syntax:

mv <source> <destination>

Example

mv file1 file2 (now the file1 is changed to file2)

Move Command



A file isavailable inthe name of

one in thedirectory old



Move Command



The file one isshown above in thenew directory

Move Command



Here a file iscreated test

in the old directory

Move Command



This exampleshows how to

rename a filetest to tested

Move Command



Using the l lcommand, theabove screen

shows therenamed file

rm and rmdir commandrm : This command is used to remove files

Syntax:



y

rm <filename>Example :

rm file1

rmdir : This command is used to remove directories.

Syntax:

rmdir <directory name>

Example :rmdir linux

rm command



This screenshows the

contents of thenew directoryThe above rmcommand is

used to remove

the file k

rm command



Here the file named

k is removed fromthe directory

rmdir command



Here a directory iscreated named donic

which is removed throughthe command rmdir



rm command



Using rm withoption – r, the

directory alongwith contents canbe removed

rm -r command



Now theabove screen

shows that

the directoryis removed

rm command



The above

screen showsthe contents of directory jerry

rm -ri command



The rm with –ricommand is

used to remove

the contentsinteractively.

rm -ri command



We can see that thefile for which we havegiven ‘y’ is removedand ‘n’ is preserved

The file command is used to check the file content.

File command



Syntax :

file <filename>

Example:

file f1 (f1 is a file. File will show the format)

file /dev/fd0 (The output shows that the fd0 is a

block special file)

File formatThe file along with

file name (ss) shows



the file format



more



l l commandshows the

contents atonce.



more



More is usedto lists the

contents onescreen at atime

more



More is beenprompted

after listingone by one

more



Here it isthe sameprocess

listing morecontents,shown as

above

more



Now themorecommand is

over andwe are inthe end of the page

vi & vim editor

Vi is known as the visual editor.



It is a standard editor under Linux and Unix system.

Vim is the improved version of vi editor

Vi have three modes of operation•Command mode

•Insert mode

•Esc mode

vi Modes

Command mode:

Operations such as cut copy paste delete



Operations such as cut, copy, paste, delete,

undo, redo etc., are done in this mode.

Insert mode:

Type in new text

Ex-mode :

Extended commands for saving, exiting, search-and-replace can executed here

Working with vi editor



exam is afile created

or openedwith the vieditor.

Command Mode



Press ‘i’ toget into

the insertmode

Insert Mode



This is theinsert mode



Ex- Mode



Press:wq to

write andquit



Yank



Hit escape andtype 3yy to yankthree lines from

the cursor position

Like this example,

you can copy anynumber of lines bytyping numbers of

lines and yy

Text yanked



In the previousslide, we saw how

to yank the text.After yanking wesee the message

as below

Text put



Now the yanked

text is pasted fromthe cursor position

by hitting the ‘p‘

delete



To delete text, place

the cursor in thebeginning of the lineand give the totalnumber and dd

delete



Now 3 lines aredeleted andmessage get

displayed as 3fewer lines asshown below

cut and put



To cut a lineafter curser

position hit 1cc.

cut and put



Get into insert modeand place the cursor

where the data shouldbe pasted. Press escto get in to command

mode

cut and put



Now hit p topaste the data.

Search



Get into ex modetype / followed by

data to besearched andpress enter

Search



When we press enter

it shows the firstfound match from

bottom to top.

Search



Then if we press ‘n’ it willshows the second match

for that data.If we continuepressing n it will showsuccessive matches.



Find command



This command

searches thepassword file from

/ directory.

Find command



The above

screen showsthe execution of

command

Locate command

Locate:



To search or locate files and directories from the

database.

It locate the files faster than the find command

Syntax:

locate [pattern]

Locate command



To search file

named test1from database.

Locate command



All the files anddirectories named

test1 is locatedand displayed.

man :

f f

Man command



Display helpful information about

commands.

Syntax:

man [option] command

Option:

–k - search by command description rather than

command name.

Man command



It displays manualpages for lscommand.

Man commandThe manual pageof ls command is

di l d h



displayed here.

Enter q to exitfrom manual page.

useradd :

To create a new user account and login

di t f th t t

useradd command



directory for that new account.Useradd will create new entries in system files.

Syntax

useradd [options] [user ]

Options-c Comment field.

-d Home directory

-e Account expiration date.

useradd command

User namedabdulkalam is

t d



created.

To set passwordfor abdulkalam.

useradd commandEnter thepassword.



User home directory



When new user account is

created ,a logindirectory for theuser is created in

/home dir.

User configuration files

When a new user account is created, its entries

updates the following system files.



- /etc/passwd

- /etc/group

- /etc/shadow

Passwd fileTo view

password

fi ti fil



configuration file.

Passwd file



First fieldrepresentusername.

x representsencryptedpassword isavailable inshadow file.

User id.Group id. User homedirectory.

User loginshell.

Shadow file



To viewshadow file.

Shadow file

Encrypted

password for



password for the user

abdulkalam.



Group id for

the user

Groups file



the user abdulkalam.

User loginAbdulkalamlogging in .



User loginUser

home dir or login dir



User account canbe deleted through

userdel command

userdel command



userdel command

Creating groupsNew group is created by hand-editing the file /etc/group or by using

groupadd command.

Syntax:

groupadd groupname



groupadd groupname

groupdel command is used to remove the group.

Syntax

groupdel groupname

Groupmod is used to rename the existing groupname.

Syntax:

groupmod –n newname oldname

Groupadd commandA group is added inthe name of india byusing the command

groupadd



groupadd.

Usermod command



Using usermodcommand the user

abdulkalam isadded to group

India

Groups file

To view

group file



group file

Groups file



The last field shows

the user abdulkalamadded in India group

The id number

assigned to the groupindia is 501

Groupdel command



Groupdelcommand deletes

window group.

Group Administration



Create a directorynamed product

and group namedsales.




User’s are added inthe sales groupusing usermod

command.




Open thegroup file.




This shows that thethree users are

added in the salesgroup.




Change the group name

sales to product directoryusing chgrp command.




The screen showsthat the changesbeen made in the

group field.




Three files createdunder product directory.




The permissionfor the product

directory ischanged.



suresh logs in terminal. Ashe is the member of the

group, he have theprivilege to access the file.




rajesh logs in terminal. Ashe is the member of the

group, he have theprivilege to access the file.




tom logs in terminal. he isnot the member of the

group so does not have theprivilege to access the file.




The above screenshows the permissionbeen restricted to the

user tom.

Changing owner



The chown

commandchange the file or directory owner.

After giving thechown command

the owner ischanged fromroot to suresh.

Changing owner



The owner and

group name canbe change usingchown command.

chage commandThe chage command let you specify an expiration limit for a

user's account and password .

– Syntax:



ychage [option] username

Option

-l lists the current password expiration.-m set the min. days to change the password.

-M set the max. days to change the password.

-E specific expiration date for user account.

-I set inactive period (in days)

-W warning period, number of days beforeexpiration.

User administration



Chage –l : liststhe account and

passwordinformation of

user tom.

This field sets

the password for the maximum

valid days given.

Inactive period is

used to givegrace time tochange thepassword.

User administration



The –M

command with100 sets as themaximum days.

The password

expires field isupdated by +100days from user creation date.

User administration



Allowableaccount inactivity

period after which password

will expire.

User administration



The -W optionshows the

warningmessage before

expiration.

User administration



The -m option for minimum

number of days auser can existswith password.

The -E option isfor specific

User administration



pexpiration datefor an account.

Set userIDIt allows an executable file to run under the user or group

security context with the permission of its owner.



SUID can be set as follows:

• chmod u+s [filename]

(or)

• chmod 4xxx [filename]

Set userID



The above screen

shows file shadow andpassword along with

the set user idpermission.

The passwd is thecommand which updates

the password in theshadow file, instead of not having the execute

permission.

Set userID



Tom changes the

password usingpasswd command.

Set userID



The set userid

permission isremoved from the/usr/bin/passwd

file.

Set userID



Now we can view

that tom user cannot changethe password.

Set GroupID



The user suresh

logs get into theproduct directoryand create a file.

The user sureshwho create a file,the group name is

assigned as suresh.

Set GroupID



The groupid is

set to theproduct

directory.

Note: the group sales

is added to theproduct directory.

Set GroupID



After setting the group

id, user suresh createsa file win98. Using thecommand ls –l showsthat the file is createdunder the group sales.

Sticky bit



The user rajesh logsand he removes thefile bios created by

suresh.

The files remove ispossible because

the sticky bit is notset to the productdirectory.

Sticky bit



Using +t option the

sticky is set to theproduct directory.

Sticky bit



After assigning the sticky

bit, user rajesh try todelete the file created by

other user but he isunable to do it.

Switch user

su command is used to switch to another account from

the command line.



This command is most often used by system

administrator to temporarily become the root user

without logging out of their non-privileged account.

Syntax

su - [user] -c command

Switch user



Here the root user

switching to another account.(user joe)

Switch user



It executes rootprivileged command

from the ordinary user account.

Multi user loginLike unix operating system where multi user login can

be done, in same sense the Linux operating system

supports multi user login.



Each user can login in each terminal and can do multi

processing which avoids logging off from the system.

Multi user

t i th



tom, is the user who log in thefirst terminal

Joe, is theuser who log

Multi user



gin the second

terminal

Multi user

harry, is theuser who log



gin the third

terminal

Multi user

wilson, is theuser who log



gin the fourth

terminal

Multi user

bill, is the user who log in the



who log in thefifth terminal

Multi user thano, is the

user who logs

in the sixthterminal



terminal

W is the commandto list the users

logged in



Advanced Uses of VI and VIM

File RepositioningPress G, Cursor go to last line of a file.

Press 1G, Cursor go to first line of a file.

Press Ctrl+f, Cursor forward one full screen.



Press Ctrl+b, Cursor go back one full screen.

Press Ctrl+d, Cursor go down half a screen.

Press Ctrl+u, Cursor go up half a screen.

Screen Repositioning

Press H, Cursor go to first line on screen.

Press M, Cursor go to middle line on screen.



g

Press L, Cursor go to last line on screen.

Press Z+Enter, Make current line is first line on screen.

Press - (hyphen) Make current line last line on

screen.

It is also possible to read a other file content in your current files.

The following command help you :

– Go to exmode in a vi editor

Advanced Reading and Saving



– Syntax : r <filename>

– Example :r /root/file1

While working in a editor we can copy the file content toanother file

– Syntax : starting line, endingline w <file name>

– Example : 1,20w file2 – Example : 21,40w >> file2

FilteringA powerful feature of vi is the ability to include into your document

the output of Linux commands.

For example if you want to display any command output in your filesee following syntax



see following syntax .

!!command

The syntax will be working in exmod in editor.

For example to display date ,type following command in exmod.

!!date

Filtering

Open the filein vi mode.



v ode.



The output of the

date command iswritten here.

Filtering



Sed CommandSed command just like find and replace .

To display a file the Sed command change the



To display a file , the Sed command change the

particular word in standard input only , but not

change original content of file.

Example of Sed command .

sed ‘s/ram/raju/g’ /root/file1

Sed Command



The output of the

named.local is

displayed.

Sed Command



Here sed command displays the

output by replacing the localhost

as www.example.com, but it

wont write output in the file.

ex mode : search and replacevi can perform search and replace operations much

like sed command.Syntax:



Syntax:

ex mode:1,$s/searchname/replacename/g

1,$ - address starting from line one.

s - String of character

g - replace multiple matches in a

line

ex mode : search and replace



Open the file

in vi mode.




It searches and

replaces the localhost

as www.example.com.




Thus the localhost

was replaced aswww.example.com

..

It is also possible to read a other file content in your current files.

The following command help you :

– Go to ex mode in a vi editor – Syntax : r <filename>

E l / /fil 1




– Example :r /root/file1

While working in a editor we can copy the file content to another file

– Syntax : starting line, ending line w <file name>

– Example : 1,20w file2

– Example : 21,40w >> file2




Here you can view

output of test file.

Open a file in vimode.




To display the

output of another

file named test inthe current file.




The output of test

file is displayed..



To write the contents of

the existing file in

another file named test1.




The contents are

appended to the

test1 file.




You can see the

appended contentsin the test1 file.

Configuring VI and VIMNumber of configuration are available in vi editor, see some of

example .

:set number - shows a line number on the left margin in a vi

editor



:set showmatch - when a right curly braces or a right paranthesis

is typed, a cursor will jump to the matching left curly braces or left paranthesis.

:set all - it shows all configurations.

Set number



File contents.

Set number



To assign numbers

to all line in vieditor.

Set all

To view all the



possibilities of

configurations

available in vieditor.

All the available

Set all



option are

displayed here.

Redirecting Input and OutputOuput of a command is redirected to a file

– Command > filename

Example ls -l > /root/file1

Example ls -i >> /root/file1



Output of file redirected to a command

– Command < filename

Example - cat < file1

• Error message of a command redirected to a file

- Command 2> file1

- Command 2>> file1

- Example – ll –L > file1

The output of ls

command isredirected to the

H h fil i

Redirecting Input and Output



file named ex.Here the file is

overwritten by the

output of lscommand.

The output of lscommand is

di t d t th




redirected to the

file named ex1.




Here the output of

ls command is

appended to theex1 file.

Redirecting InputA command which accepts the input from a file is

known as Redirecting Input.

Syntax - command < file1



Example : tr ‘A-Z’ ‘a-z’ < file1

A file is created in the name file1 and text is entered

in capital letters, which is redirected through < symbol

and the command translates the data to small letters.

l h




tr translates the upper case

letters to lower case.Here

output of file v isredirected as input to the

tr command.

2> redirects the

error messages tothe ex file.




Here we can see

redirected error

messages in the ex

file.

Piping

Pipes is used to execute more than one command at a time. See

following command.

Syntax : command1 | command2



Example: ls -l | more

It is also used to execute command result

Example: cat file1 | grep station



Redirecting Both Standard Output And Error

If find command is executed, its output can be stored in file2. if

error occurs during execution, the error message is stored in



file1.

For example:

find / -name passwd 2> file1 >file2



tee Commandtee is useful to save the output at various stages from

a long sequence of pipes.

Example: ls | tee a1 | ls –l | tee b2



Example: ls | tee a1 | ls l | tee b2

The above example shows the types of ls commandsand options are used to store output to the files g1,g2 and g3.

tee Command

It saves the output

of ls in file a1 and



output of ls –l in

file b2.

grep commandgrep

- means general regular expression processor.

-it analyze the content of a file a line at a time,

returning a line that matches a pattern.



grep command



Grep prints the

pattern matched

with ganesh in the

file /etc/passwd.

awk command

An awk program searches for lines in a file

and performs some action on those lines.



Example:

awk ‘/bash/ { print }’ /etc/passwd

awk command



awk display first

field of the

/etc/fstab file.

File CompressionsSeveral compression utilities are available for use on

Linux and Unix system.

But most software for Linux system use threecompression utilities.



compression utilities.

1 - compress2 - GNU gzip

3 - bzip2.

Compression commandcompress:

It compresses a file and give the extension as .z for that file.

Syntax:compress <filename>



uncompress:

It uncompress the compressed file.

Syntax:

uncompress <filename>

Compression command

This

compresses

The actual

size of file is107 bytes.



the file a.

Thus the file

size is

compressed to39 bytes.

The compressed

file is indicated bythe .z extension.

This

uncompress

the file a.

Compression with gzipgzip utility compresses file .

gunzip decompresses them.

To compress a file, enter the command gzip and the

filename.this replace the file with compressed



version of it,with the extension .gz.

To decompresses a gzip file use command gunzip.

Syntax:

gzip filename (compression)

gunzip filename.gz (decompression)

Compression with gzip

The actual


gzip command

compresses the



file a.

The compressed

file is indicated bythe .gz extension.

Thus the file

size is


This

uncompress

the file a.

It compresses files using the burrows-wheeler block-sorting text compression algorithm and huffmancoding.

You compresses files using the bzip2 command anddecompresses with bunzip2.

Compression with bzip2



The bzip2 command create a file with the extension.bz2

Syntax:

bzip2 filename (compression)

bunzip2 filename.bz2 (decompression)

Compression with bzip2

The actual


bzip2 command

compresses the

fil



This

uncompress

the file a .

file a.

The compressed

file is indicated bythe .bz2 extension.

Thus the file

size is


Creating ArchivesTar:

tar command is used to create archives on device or files.

Originally, tar was used to create archives on tape devices, hence

its name stands for tape archive.



When creating a file for a tar archive, the filename is usually given

the extension .tar.

While tar is seldom used to back up entire file system.



tar command

It create

backup for thefiles a,b,c,d,e

and f in



backup.tar.

The backup

files are

indicated by

.tar extension.

tar command

tf options

display all thefile in backup .



tvf options

displays along

with the user

and group

names.

tar command

If incase wemiss the file

then we can



extract those

file back using

xvf options .

Printer-configuration



g

Printer-configurationCommand to

configure the

Printer



Click New

option toadd printer

Now the system isloading printer

information




information.




Click Forward

option to add

printer queue




Chooselocally-connected

option for localprinter




Choose

forward option to

proceed to next step.

Choose any one the

manufacture name




manufacture name

in he list.




Choose the serial

number of the

printer




Choose apply

option for

What you haveselected

Now the printer configuration

are been

l i th




applying the

changes to the

system




Choose yes you will be

getting an test page form

the printer

lpq is a command to

view the queue in printer




lpr is a command given




lpr is a command given

to print particular file.

lpq is a command to

view the queue in printer




Introduction to process

Linux treats each task performed on your system as aprocess, which is assigned a number and name.

You can examine this process and even stop them.



Red Hat provides several tools for examining processes

as well as your system performances.

The process is easy monitoring is provided by severalGUI tools,like Red Hat Procman System Monitor.

ps Command• ps command is used to list the process.

• To display a information about process specific to

the active terminal.

• Syntax: ps [option]

• Options available:

-a : To display all process, not including



process not controlled by a terminal

-x : To include all process not controlled bya terminal, such as daemon process.

-l : To long list including more information such

as process owner's user id.

-u : To display user name of the processowner.

-e : To view the all process id

pstree command

It shows the

process ancestryfor all process

running on the



system.

ps –a command

Display all

processesexcluding

processes not



controlled by

this terminal..

It li t th

ps –l command



It list the

processes along

with the owners

id.

Display all

processesincluding

processes

ps –x command



controlled by

this terminal.

ps –u command



It list the

processes alongwith the user

name.

kill process

• Kill command is used to send a particular process to

get clear.

• Syntax : Kill -9 <process id>



• ps - aux is the command to view all process name

and id

• Example: kill -9 3743 (This example shows the kill

command, option and the process id to kill.)

It kills the tty2

terminal bash

processes

kill process



processes .

Altering process schedule

• renice is the command to set the priority of a process.

• The priority value can range from -20 (highest priority)

to 19 (Lowest priority)



• Syntax : renice - +(minus symbol or plus symbol)

<priority number> -p <process id>

• Example : renice -15 -p 1970

Foreground and Background process

• Fg command is used to run the background process in

the foreground (Front End)

• jobs command helps you to view the background

processes.



• Step 1: jobs <enter> to view the process

running and job numbers

• Step 2: fg %2 (job number)

• bg command is used to resume the suspendedcommand in the back grounded.

‘&’ makes the

command to run

in background.Jobs displays the




in background.Jobs displays the

processes running

in the background.

Fg bring back the

back grounded




back grounded

processes to the

foreground.

Here the

command is

suspended

whileexecution by

pressing ctrl+z.Bg resumes the




Bg resumes the

stopped jobs to

the background.

Bash Shell Scripting

Scripting basics

– A shell script is a text file containing set of commands.

– Scripts are useful for automating process that you perform

repeatedly at the command line.

– Instead of typing commands, the commands are executed

through scripts.



g p

– For example : Every morning when you login you can

perform following operations.

• Checking system date and time

• Checking email

• How many users have logged in the server.

Creation of shell scripts

Shell script are written in vi editor

The very first line, mention what type of script is used

– For example:

• #!/bin/bash used for bash shell script

• #!/bin/sh used for borne shell script



• #!/bin/csh used for C shell script

• #!/usr/bin/perl used for Perl shell script

• #!/usr/bin/python used for Python shell script

Basic bash shell script

How to print a data in a console

– echo “Red hat” <enter>

How to execute a command in echo statement

– echo “hostname `hostname` “ <enter>



– echo hostname hostname <enter>

How to execute a variable in echo statement – A = 10

– echo “A value: $A” <enter>

Execute bash shell script file

Two methods available to execute a script file are

– First method is

• Syntax :

» bash filename

– Second method is



Second method is

• Syntax :

»Give the execute permission the script file

through chmod command

»Run the file by ./<file name>

Get in tothe vi editor

to createscript file




It denotes weare usingbash shell

scripts

Thi i t




This scriptexecutes the

system hostnameand date

Executing script - First Method

Bashexample

(file name)to executethe script

Output is



Output isshown in the

terminal

No executepermissionfor a file in

default

Executing script - Second Method



Permission

is set to thefile, asexecutable

Second Method

./ example(file name)to execute



the file

Arithmetic Calculation

Examplescript file for calculation



calculation

Arithmetic Calculation

Using readstatement weread the value

for A and BUsing expr we can

add values



The values are

entered for inputThe output isdisplayed



Partitions

The Linux supports four primary partitions and many

logical partitions in the extended partition.

The Linux kernel supports maximum number of 63



partitions on each IDE disk.

And maximum of 15 partitions on each SCSI device.

Partition Types

Linux-specific partitions would normally be one of the

following types with a unique ID.

0 X 5 - Extended

0 X 82- Linux swap



0 X 83- Linux0 X fd - Linux RAID

0 X 8e- Linux LVM

Partitioning

In Linux, partitions can be created by either of the

following three utilities

– fdisk

– sfdisk



sfdisk

– disk druid (only available during installation)

– GNU parted

fdisk

fdisk

- Fixed Disk

- Menu driven programs to create anddelete partitions



Before starting fdisk, identify the hard disk type that is

whether primary master or slave and secondary

master or slave by using command fdisk -l.

l option list the

available

partitions

Total hard disk

space with total

heads, sectors and

cylindersAvailable partitions,

hdb t th t th

Star indicates

Starting and ending

cylinder for each

Size of the

i i i bl k

Partitioning with fdisk



hdb represents that the

hard disk is connectedas primary slave

the boot

partition.

cylinder for each

partition onecylinder = 8.3MB

partitions in blocks

To create partition

in the device hdb




Type h or help to

shows list of

available commands




in fdisk

Type p to display

the available




the available

partitions



Enter the ending

cylinder or type thesize in MB.

Type w to save and




Type w to save and

exit from fdisk.

Instead of restarting to

update the partitiontable just enter the

command partprobe.




Thus a new




Thus a new

partition namedhdb6 is created

Red Hat Linux Filesystems

Red Hat supports following filesystems.

- ext2

- ext3



- minux

- reiserFS (under research)

ext filesystemsext : Extended filesystem.

ext2 : Older standard Linux file system supporting for filenames and

large file sizes.

ext3 : Standard Red Hat Linux file system, used for all hard disk

volumes under Red Hat Linux by default.



It is the extension of ext2 with the feature of journaling (aware of

unexpected power outages and disk errors)

minux & reiserFS

Minux : This file system is small , simple and mostlyused for floppy disk .It support filenames up to 30characters.

ReiserFS : It is advanced journaling filesystem stillunder development for Linux.



Its main difference between ext3 and reiserFS .Its usedisk resource efficiently and is particularly effectivewith file system containing many small files and largedirectories

Creating file system

Once you create a partition, you have to create a file

system on it.

To do this, use the mkfs command. To build the Linux

file system and pass the name of the harddisk



partition as a parameter.

Syntax:

mkfs -t <filesystem type> <partitioname>

Creation of file system

Current partitions

are displayed here



are displayed here


Hdb6 7and 8 are



Hdb6,7and 8 are

newly created partitions.


It creates ext2file system for

the device hdb6.



To view the file system type

Dumpe2fs : this command is used to view which file

system we are using.

Syntax :

dumpe2fs <partitions>



p p

Example:

dumpe2fs /dev/hda1

To view the file system type

It displays the

file system

information's.



Sparse_super

represents the

ext2 file system.

Mke2fs command

Mke2fs : This command is used to create file system.

Syntax :

mke2fs [options] device

Example:

mke2fs /dev/hda1 (it will create ext2 filesystem for



mke2fs /dev/hda1 (it will create ext2 filesystem for

hda1 partition)

mke2fs –j /dev/hda1 (it will create ext3 filesystem

for hda1 partition)


It creates ext2

file systems for

device hdb7.



View the file system type

S



Sparse_super

represents theext2 file system.

Converting ext2 to ext3 file system

It converts the file

system of hdb7 from

ext2 to ext3



View the file system type

has_journal

represents the ext3



p

file system thus theext2 is converted to

ext3

Mount command

In Linux, like any

other device the

partitions should be

Mount the partitions

hda6 in data1

directory and hda7 in



partitions should be

mounted.

directory and hda7 in

data2 directory.

Tune2fs command

tune2fs : It is a command used to converting from

ext2 to ext3 file system without un mounting..

Syntax :

tune2fs –j <partitions>



tune2fs j partitions

Example:

tune2fs -j /dev/hda1

View the file system type.

Ext2 is the current

fil f h



file system for the

device hdb6.

Tune2fs command

Here it converts the

file system for hdb6

from ext2 to ext3



from ext2 to ext3.

View the file system type.

Now the file

i d



system is converted

to ext3 file system.

Repair Filesystem

e2fsck : This command checks the consistency of the

file system and repair it if it is damaged, you can use

file system checking tools. Example : e2fsck /dev/hda1

fsck : This command checks and repair a Linux file



system. Example : fsck /dev/hda1

The main difference is e2fsck it will work in ext2 and

ext3 filesystem and fsck will work only in ext3 filesystem.

Repair Filesystem

fsck and e2fsck are



the command usedto check and repair

the file system.

Disk usage

df and du are used to check the disk usage.

df : It reports the amount of space used and

available on a mount file system as reported.



du : It displays directories entries and the number of

data block assigned to them.

df command

df command

displays the space

used and available

in the mounted file

systems

df -h, displays size

in human readable

format in the power



df -H displays the

size in the power

1000 instead of

1024.

format in the power

of 1024

du commanddu command displays

the estimate file space

usage available

df -h & H, displays size

in human readable format

in the power of 1024 and

1000 respectively



1000 respectively.

Performance tools

free command lists the free ram memory and as well as

what is used for buffers and swap memory.

top command lists the most CPU intensive processes.



Vmstat shows the performance of system components.

free command

free command

display

information

about free and

used memory



used memory

on the system.

vmstatReport virtual

memory statistics



topDisplays top

CPU processes



top



It displays the

listing of most

CPU-intensive

tasks on the

Some process start at boot time and continue runninguntil the system is shutdown. Such process are

known as daemon processes.

Two types of daemon process:

Daemon Process



standalone daemon

Transient daemon

Standalone daemon are a program that run all the time

and are started up either directly by init or by a startup

script under /etc/rc.d.

Daemon Process



Transient daemon are only started up when they areneeded, and are controlled by a standalone daemon

called xinetd.

checkconfig command

The chkconfig command can also be used to activate anddeactivate services.

The chkconfig --list command displays a list of systemservices and whether they are started (on) or stopped (off)in runlevels 0-6.



At the end of the list is a section for the services managedby xinetd.

chkconfig can also be used to configure a service to

be started (or not) in a specific run level. For

example, to turn httpd off in runlevels 3, 4, and 5,

use the following command:

checkconfig command



use the following command:

chkconfig --level 345 httpd off

--list options

used to list the

checkconfig command



service.

--list option

lists xinetd

checkconfig command



services also.

--list option list

httpd service

status on

This command

httpd service is

--list options

used to list httpd

checkconfig command



status on

runlevel 0-6.

p

stop on runlevel3-5.

service status .

--del option deletes

all links for the

--list options shows

sendmail service is

--add options used

to add a service,

Now --list

options used to

checkconfig command



service in allrunlevel directories.

not there.creating links indefaults runlevels.

list the httpdservice.

Standard Boot loader

• There are two standard boot loader are used inLinux

• GRUB

• Grand unified boot loader

• LILO



• LILO

• Linux loader

GRUB

• GRUB Grand Unified Boot Loader

• is a multi boot loader that operates similar to LILO and

default boot loader for Redhat Linux.

• Using GRUB user can select operating systems to run from

a menu interface displayed when a system boot up



• Supports MD5 password protection, a boot menu editingmode and a shell like command line interface available at

boot time.

LILO

• LILO means Linux loader

• LILO is a program written to boot sector of a disk that loads

the OS and starts execution.

• It is an older version of boot loader of Red Hat Linux.



• LILO loads the Kernel based on its actual sector location on

the disk , rather than its file name

• /etc/lilo.conf - Configuration file

• lilo -v - To install or update the lilo

boot loader.

• lilo -t - Test the configuration beforeinstallation.

LILO



• lilo -u - To restore the MBR backup.

• Grubby - bootloader-probe : to showthe a current boot loader.

Lilo installation

Check the

presence of

the lilo

package.



Copy thelilo.conf.anaconda

to lilo.conf (lilo

configuration file).

lilo –vinstalls lilo

boot loader.

Thus the lilo

boot loader

is installed.

Lilo installation



This command displays

the current boot loader,

thus we can see the lilo

got installed.

Open the lilo

configuration file.

Lilo installation



Prompt presents to

boot promptwithout any user

intervention.

Denotes the

first stage

boot loader.

Locates the

second stage

boot loader.

To display a

text message

at boot time.

Boots the

kernel image.

Incase of dual

Specify which

OS will be

loaded by

default.

Lilo installation

Before booting

the OS it will

wait for five

seconds.

It specifies the file

that contain



Incase of dual

OS it boots the

other.

images to beloaded it to initial

RAM disk.

Prompts the user for

a password before

booting this image.

This will prompt for

password only when

we go to single user

Lilo installation



g g

mode.

This will update the

lilo configurationfile.

Lilo installation



• /boot/grub/grub.conf

• This is configuration file for grub boot loader.

• grub-install /dev/hda

GRUB installation



• To install the grub boot loader in hda device.

• grubby –bootloader-probe

• To show the current boot loader .

Open the grubconfigurations

file.

GRUB Configuration



GRUB Configuration



The options rhgb quiet

will start xserver

while booting.

Remove this options

to boot through text

mode.

Grub Configuration



Save the file

and exit.

Now reboot the

system.

GRUB Configuration



GRUB Configuration



Now system is

booting in text mode .

GRUB Configuration



Now system is


GRUB Configuration



Now system is


Open the grubconfigurations

file.

GRUB Configuration



GRUB Configuration



The options rhgb quiet

will start xserver

while booting.

Now reboot the

system.

GRUB Configuration



GRUB Configuration



Now system is

booting ingraphical mode.



In EL-4 redhat-config-

* tools are renamed as

system-config-*.

GRUB installation

Now the

boot loader

is lilo.

To install grub loader

use the command

grub-install /dev/hda .



Open the

grub

configuration

file.

GRUB installation



If default is

set to zero

then it boot

through first

stanza.

Label for

first stanza.

Label for

d

Flash screen to

be displayed at

boot time.

This represents that the

following files are in 5th

partition of the hard disk

on hd0.

Boots the kernel

image.

It loads the initial

RAM disk.

Loads the

dual OS.

GRUB installation



secondstanza.

To set password

to the grub boot

loader.

It gives us the encrypted format of the

password. This password is supposed to

b t d i th b f fil Thi

GRUB installation



be entered in the grub.conf file. Thiscan be done by the following method.

Following the above

command type the password

two times, this will append

the encrypted password to the

GRUB installation



grub.conf file.

Open the

configuration

file.

GRUB installation



Here we cansee the

appended

password.

GRUB installation



Just cut andcopy the

password

here.

GRUB installation



Save the file and

restart the

system.

Here you can see thegrub loader prompting

for the OS to boot.

Type p to enter

grub password if

you want to go to

single user mode.

GRUB installation



Enter the

password

here.

GRUB installation



Change the command

prompt to get in tosingle user mode to do

that press ‘e.’

GRUB installation



Enter 1 to get in

to run level 1

GRUB installation



to run level 1.

Press b to boot.

GRUB installation



Red Hat Packet Manager (rpm)



• rpm command is used to manage and install software

packages.

• This command performs installation, removal and

verification of software package.

• Each package is actually an rpm packages.

• rpm consists of an archive of software file and

Using rpm command



information to install.

• Each archive is resides as a single file with a name that

ends with .rpm

rpm command is used either for installing or uninstallingpackage.

Syntax:

rpm [parameter] package name [options]

parameter:(hyphen) -i - Installs package.

-U - Updates package.

-e - Remove a package.

-qi - Displays information for an installedpackage

Using rpm command



package.-ql - Displays file list for installed package.

-qpi - Displays information from an rpm package file.(used for uninstalled packages)

-qpl - Displays file list from an rpm package file. (usedfor uninstalled packages)

Options:

--force - Forces installation despite conflicts.

--nodeps - Install or remove without doing any

dependency checks.

aid Automatic dependency to install a package

Using rpm command



--aid - Automatic dependency to install a package.

(While available of package rpmdb-redhat

aid option will work)

Querying the packing

rpm –q acommand for

querying a

particular package



rpm –q checkswhether the above

package is installed.

rpm –e commandwill remove thehttp package.

Using rpm command



For installing the package we must the

mount the operating

system cd-rom of

RHEL and then only

we can install the

Using rpm command



we can install the

packages.

Go to

Using rpm command



Go toRedhat

directory.

Using rpm command



Go to

RPMS

directory.

List the files in

RPMS directory

and we can see

that the packages

Using rpm command



that the packages

end with an

extension .rpm.

rpm –qpi showsthe informationabout the packagebefore installation.

Using rpm command



rpm –qplshows the

list of files ina package

beforeinstallation.

Using rpm command



rpm –ivh is

to install a

package.

Using rpm command



rpm -Uvh, to

upgrade a package.

Using rpm command



rpm –qi

shows theinformationabout the

package after

installation

Using rpm command



installation.

rpm –ql showsthe list of files in

a package after installation.

Using rpm command



To view an IP-addressTwo methods available in linux to view the ip address

ifconfig :

-shows the ip address of the active interfaces with hardwareaddress.

-it can show ip address of a particular interface by taking the interface

name as argumentexample:

ifconfig eth0

ip a :

- simply shows the ip address of all interface.



Ifconfig command

Displays

information onall currently

active interfaces.



Here it displays

the information

of eth0 interface.

Ifconfig command



ip a command

Here it displays the

information about

all the interfaces.



ifup / ifdown commandIfup:

-ifup command is used to activate the interfaces.

Syntax:

ifup <interfacename>

Ifdown:

-ifdown command is used to deactivate the interface



ifdown command is used to deactivate the interface

Syntax:

ifdown <interfacename>

It deactivate the

ifup / ifdown command



It deactivate the

the interface

eth0.

Now you can

notice the interface

eth0 is deactivated.




It activates the

interface eth0.




Now you can

notice the interface

eth0 is activated.




In linux ip address can be assigned by the following methods.netconfig:

- to assign permanent ip address to the interface

Ifconfig:

- to assign temporary ip address to the interface.Syntax:

ifconfig <interfacename> <ipaddress> subnetmask<subnetmaskaddress> broadcast <broadcastaddress>

Ip a a :

- to assign additional ip address temporarily

Assigning ip address



Syntax:

ip a a <ip/subnetmaskaddress> dev <interfacename>


To assign permanent

ip address using

netconfig command.



Press yes to assign




Press yes to assign

ip address.

To assign ip




To assign ip

address

automatically

from dhcp server.

To assign ip




o ass g p

address manually.

Using ifconfig

command ip

address can be

assigned.ip a command




ip a command

shows the

assigned ip

address.

As said earlier,

ifconfig is used to

assign ip addressil

When network

service is restarted,the ipaddress

assigned through

ifconfig to the

device is removed.




temporarily.

To update ip

address thenetwork service

is restarted.

ip a command




p

shows the

assigned ip

address.

ip address can be assigned

temporary using

ip a a command.




Ip address can be

removed using

ip a d

command, once

network serviceis restarted it get




is restarted it get

removed.

Router configuration

The ip_forward file is

assigned 1 for enabling

the router or 0 for

disabling.( Thisprocess for



process for

temporary.)

To enable the router

in permanent way get

into the sysct1.conf.



The 1 is assigned toenable the router and



enable the router and

this file is for setting

router in permanent

manner.

Gateway can be addedusing the command



using the command

route add.



ping command

It is used to detect whether a system is up andrunning.

Syntax:

ping [options] <domainname>or

ping [options] <ipaddress>

Options:

a - audible pingb - to ping the broadcast address



b to ping the broadcast address

c - stop sending packets after count.

It checks whether

www.example.com

is up and connectedto the network

ping command



to the network.

ping command

It checks whether

192.168.0.253 machinei d t d t



is up and connected to

the network.

-b option used

to ping a broadcast

address.

ping command



-c options stops

sending packets

after the

specified count.

ping command



• LVM structure

• In this structure the LVM physical partitions are

also known as extents, are organized into logical

groups, which are in turn used by logical volumes.

LVM Structure



Physical volume

• Physical volume:

• It is nothing but hard disk partition that you create

with partition creation tools such as parted or fdisk.

• The partitions type can be any standard Linux



partitions type, such as ext2 or ext3.

Volume groups

• Physical volumes are organized into logical groups,known as Volume groups

• Volume groups that operate much like logical harddisk.



• You assign collection of physical volume to differentlogical groups.

Logical Volumes

• A logical volume is a virtual partition.

• One or more physical volumes to be combined in tovolume group to construct logical volumes.

• Logical volume can be created in logical groups.



• It functions much like hard disk partitions on a

standard setup.

lvm



Create partition

using fdisk command

Type p to check

how many

partitions available

in hard disk

LVM Configuration



Here 4 partition

is created with

equal sizes of

100mb through

n option.

LVM Configuration



Newly created

partition is

listed below as

hdb6,7,8 & 9.

To know the

LVM Configuration



To know the

partition id, use

the option l.

Here 8e represent

lvm partition id.

LVM Configuration



Here below after

giving ‘t’ option

the partition id is

changed to lvm

We have tomention the

hex code of

the partition

To change the

partition id as lvmid, use T option.

LVM Configuration



Now

partition id is

changed to8e(LVM)

LVM Configuration



We save the lvm

partition throughw option.

Previous versions of

redhat needed to

restart system after

ti titi I

LVM Configuration



creating partition. In

current version to

avoid restart we use

partprobe.

Physical volume iscreated for lvm

partition(hda6.7.8&9)

Pvdisplay commandshow the details of

physical volume

LVM Configuration



pvdisplay command

displays the physical

volume size.

LVM Configuration



Vgcreate creates

group as test0 for lvm partition hdb6

vgdisplay command

displays theinformation about

volume group test0.

LVM Configuration



lvcreate creates a

logical volume and we

assign name as data inthe test0 group

lvdisplay,

displays the

information

about logicalvolume.

LVM Configuration



Make2fs, creates

an ext3 file

system for data.(logical volume)

LVM Configuration



The logical volumedata is mounted

to /data directory.

Open fstab file for permanently mounted

LVM Configuration



the logical volume data.

See thecontent of

LVM Configuration



fstab file.

Logical volume name isdata is mounted on

/d di

LVM Configuration



/data directory

permanently .

LVM Configuration



Here we can see free

space of logical volume

data.

Create a big file of size

40mb in /data directory.

Here we can see there isno free space available

i /d di

LVM Configuration



in /data directory .

If the space

assigned to data is

Extend the logical volume

size upto 45mb using

lvextend command.

Now create filesystem for

the extended volume using

ext2online.

After extending volume nowwe see the free space

LVM Configuration



assigned to data is

not sufficient, we

can resize the

logical volume .

available in /data directory.

Here we can see only

12mb free space ia

available in the volume

group.

LVM Configuration



Now the screen

shows that test

volume group is

increased to 200mb.

Note that the total

allocated size for

the test0 group is

100 mb.

vgextend, extends

the space from

hdb7.

LVM Configuration



The above

command shows

the increased

space of logical

volume data.

LVM Configuration



Extend the logical volumesize upto 50mb using

lvextend command.

Now create filesystem for

the extended volume using

ext2online.

After extending volume nowwe see the free space

LVM Configuration



available in /data directory.

We can remove logical

volume first we mustunmount the logical volume

LVM Configuration



g

(/data directory).

Remove themounted entry of

LVM Configuration



logiacl volume

(data) in fstab file

After removinglogical volume

LVM Configuration



save and exit the

file.

Remove the logical

volume name is data

We can remove volumegroup first we must

After deactivated thegroup will be removed

LVM Configuration



volume name is data

using lvremove

command.

decativate the volume

group using vgchange

command.

using vgremove

command.

RAID

• RAID means Redundant Arrays of Independent

Disk .

• RAID is a method of storing data across several

disks to provide greater performance and

redundancy.

• In effect, you can have several hard disks treated

as just as one hard disk by your operating system.



Types of RAID

• RAID can be implemented on a

• Hardware level

or

• Software level



Hardware RAID

• On a hardware level, you can have hard disk

connected to a RAID controller, usually a special

PC card.

• Your operating system can accesses storage

though the RAID hardware controller.



Software RAID

• You can implement RAID as software controller,

letting a software RAID controller program.

• The controller program manage access to hard

disks treated as RAID device.

• The software version lets you use IDE hard disks as



The software version lets you use IDE hard disks as

RAID disk.

Software RAID LevelsRAID levels Capabilities Description

Linear Appending Simply treat RAID hard drives as one virtualdrive with no striping, mirroring.

0 Striping Implements disk stripping across drives withno redundancy.

1 Mirroring Implements a high level of redundancy. Eachdrive is treated as mirror for all data.

5 Distributed Parity Implements data reconstruction capability



5 Distributed Parity Implements data reconstruction capabilityusing parity information. Parity information isdistributed across all drives.

RAID

rpm -q command

checks, whether the

mdadm installed



RAID

The partition is

created usingfdisk command.

Now the screen lists

the partitions.



p

The partition is

created usingfdisk command.

Now the screen lists

the partitions.

Raid Configuration



4 Partitions is

created using n

option with equal

size of 100 mb

Raid Configuration



Now use ‘p’ to

check created

partitions.

The l option, lists the

file system. The fddenotes linux raid

Raid Configuration



The l option, lists the

file system. The fddenotes linux raid

Raid Configuration



To set the

partition type use

t options.

Raid Configuration



Option p lists the

partition id and

show the changes.

Raid Configuration



We save the raid

partition throughw option.

Previous versions of

redhat needed to

restart system after creating partition. In

Raid Configuration



current version to

avoid restart we use

partprobe.

Using mdadm tool

creating raid level 5 it usefour partition

/dev/hda6,7,8&9 and

creating raid device is

/dev/md0.

Raid Configuration



Watch command

shows the onlinestatus of raid

devices.

Raid Configuration



Here we seestatus of each raid

disk.

Raid Configuration



Here we see the

ext3 file system iscreated.

Raid Configuration



mdadm –detail

command show thedetail information

about the raid

devices.

Raid Configuration



Here we see each

raid disk major &minor no. .

Its show the raid

disk status (weather raid disk active or

not active ).

Raid Configuration



Now raid device

(/dev/md0) ismounted on /data

directory.

Raid Configuration



Now raid device

(/dev/md0) is mounted

Raid Configuration



on /data directory in

/etc/fstab file for

permanently.

Now go to /data

directory and

create the file

name is file1 using

dd command.

df command show

free & used space

f h id d i

Raid Configuration



for the raid devices

& partitions.

Mdadm –query

command show theinformation about

particular raid device

& partitions.

Raid Configuration



Raid Configuration



Mdadm – manage

command set fault or fail particular

partitions (/dev/hda9).

Cat /proc/mdstat

command show disk

the disk is failed.

Raid Configuration



Here see mdadm –

detail commandshow disk

/dev/hda9 is faulty.

Raid Configuration



Now remove the

/dev/hda9 partitionfrom the raid

device /dev/md0

using Mdadm –

manage command .

Raid Configuration



Now add the

/dev/hda9 partitionfrom the raid

device /dev/md0

using Mdadm –

manage command .

Raid Configuration



Watch command

shows the onlinestatus of raid

devices.

Raid Configuration



Here we can see thestatus of online

synchronization of raid

disks.

Raid Configuration



Now the faulty

disk is replacedand we can

see the data.

Raid Configuration



Here you can see

mdadm –detailcommand show

disk /dev/hda9 is

active.

Raid Configuration



Disk quota

Disk quota is used to control how much disk space a particular

user can access.

Quota tools:

quotacheck

quotaon

quotaoff

edquota

repquota



Quota tools

Quotacheck:

It scans the file system for the current disk usage and update the

aquota.user file.

Quotaon:

It turns on the quota.

Quotaoff

It turns off the quota.

Edquota:

It is used to set disk quotas for a user.

Repquota:It displays summary of disk quotas and and the quota usage .



Implementing quota

To implement disk quota for an user, set the user quota for the home

directory by replacing its “defaults” entry with “usrquota” in fstab file.

The following slides will guide you how to implement disk quota for

particular user.



Open the

fstab file.

Implementing quota



Replace this

defaults as

usrquota.

Implementing quota



Now usrquota

is assigned to

the /homedirectory.

Implementing quota



Here you can see that

the user quota is not

updated for the /home

directory.

Remount the

/home directory

to update.

Now you can see

the user quota got

assigned to /homedirectory

Implementing quota



Create quota

database file named

aquota.user to hold

the quota

information for all

users.

It checks the

validity of quota

database of the

/home directory.

Implementing quota



Turn on the

quota.

Implementing quota



Let us set

disk quota for

the user jack.

Implementing quota



To assign the

quota for the

user jack.

Implementing quota



Blocks

represents disk

space in KB.

The maximum memory

space for a user. This will

deny the user to access, if he exceeds the quota limit.

This soft limit will

just issue a warning if

he exceeds soft limit.

Inode represents

number of files anddirectories can be

accessed by the user.

To set soft

limit for the

inode .

To set hard

limit for inode.

Implementing quota



accessed by t e use .

Here we set soft

limit as 40 KB

memory space .

Here we setsoft limit as 15

inodes .

Here we set hardlimit as 50 KB

memory space .

Here we set hard limitas 20 inodes .so that

user can access only

Implementing quota



max of 20 inodes.

It displayssummary of

disk usage.

User jack has a hard

limit(block limits) of 50KB

and soft limit of 40 KB, he

already used 10KB

User jack has a hard limit

(file limits) of 20 inodes and

soft limit of 15 inodes , he

already used 10 inodes

Implementing quota



already used 10KB. already used 10 inodes.

User jack created five files without

any warnings. But when he create

sixth file a warning message is

displayed. This indicates the user

had exceeded the soft limit

Implementing quota



had exceeded the soft limit.

Now, when the jack attempt

to create more than ten files

i.e., the eleventh file then

write failed message occurs.

Implementing quota



Here jack use ddcommand to create a

file named ‘1’ of 30KB.

Since the user exceeds

the soft limits a warning

messages is occurred.

Implementing quota



Here jack attempt tocreate a file named ‘2’ of

10KB . But since, he has

exceeded hard limit write

failed error occurred.

Implementing quota



Here we can notice that

the jack had used all thisquota. So he is restricted

to create files.

Implementing quota



mount command

Mount

Used to mount a file system

It takes two argument : the storage

device and the mounting point.

The device is a special device file that

connects the system to the hardware device.

Mounting point is directory on which the

storage device is to be mounted.



Syntax:

mount [options] <device> <mountpoint>

Options:

-w mount the file system with read/write permission.

-r mount the file system with read permission.

-t to specify the type of file system to be mounted.

-a mounts all the file systems listed in /etc/fstab.

mount command



umount command

It un mounts the mounted file system.

The removable media like floppy disk, and cd are unmounted after use, by using umount command.

Syntax:

umount <mountpoint>



mounting CD-ROM

To mount the

CDROM on the

mounting

point

/mnt/cdrom



mounting CD-ROM

Now we can access

the CDROMcontents from the

mounting point.



Unmounting cd-rom

Unmount the

CDROM

after access



Mount /unmount floppy

To mount the

floppy on the

mounting

point

/mnt/floppy.Unmount the

floppy after

access.



Mounting Hard drive partitions

To mount a hard drive partition

The hard disk partition also can be mounted likeany other file systems.

Example :

mount –t ext3 /dev/hda4 /mnt/data



To mount the hard disk partition (hda3 of ext3

file system) in /data

directory.

Mount commandlists the mounted

device.

Mounting Hard drive partitions



Mounting NFS (network file sharing) :

– Before mounting we must know the filesystem are exported by a remote

system. The following command is used to know the directory shared.

showmount –e remote_server

– When the host and share name are known, the following command is used

to connected the network file system to the local file system tree

mount remoteserver:/shareddir /mnt/newdir1

Mounting NFS



Showmount commanddisplays the shared

directory on

192.168.0.253

machines. .

Mounting NFS



We mount the el

directory from remotemachine into our /mnt

directory .

Mounting NFS



Mount command

shows information'sabout mounted

devices.

Mounting NFS



umount command usedto unmount remote

machine directory.

Mounting NFS



This command helpsto view windows

shared files.

Mounting smbfs



The above screens

displays window

shared directory.

Mounting smbfs



umount command used

to unmount remote

machine directory.

Mounting smbfs



Auto mount/etc/fstab:

We can also mount the file system by placing mount

information in this file.

Using entries in this file the file system can be automaticallymounted whenever the system boots.

It consists of six field per line for each file system as follows

<device> <mountpoint> <fs_type> <options> <dump_freq>

<fsck_order>



Open the

fstab file.

Auto mount



It represents

the devices.

It represents

the mount

points.

It represents

file systems.

It represents

different options

for mounting thefile system.

It represents

the dump

frequency.

It represents

the fsck.

Auto mount



Autofs

Autofs service mounts the file system automatically

when the user access the mounting point.

The autofs to supports the removable media without

recurring the user to do any thing more than insert

the media

Autofs configurations file are

/etc/auto.master

/etc/auto.misc



Autofs configurations files

/etc/auto.master:

This file specifies that a mount root of /misc will be

used for a file systems and that mounts will time out

after 60 seconds of inactive.

/etc/auto.misc:

The device to be mounted and the corresponding

file system is configured in this file.



y g

Open the

auto.master

file.




Mounting

information's

should be

entered here.




It represents

the mounting

point.

Map file having

information's about

the file systems to bemounted.

This specifies when

to unmounted the

auto mounted filesystem.




Open the

auto.misc

file.




Mounting device

information's are

t d h




entered here.

Key, the name of

the subdirectory

where the data

It represents file

system type.

It represents

the device to

be mounted.




can be accessed .

Now autofs service

is restarted.




The contents of the

cdrom is now

available in the

mounting point/mnt/cdrom/cd .




As soon as we come out

from /mnt/cdrom/cd the

file system will get

automatically unmounted




automatically unmounted

after 10 secounds.

Scheduling Task: cron

Cron Schedules one-time maintenance tasks.

Cron is ideal for setting up jobs that execute regularly at

specified times or intervals.

It contains a file which contains commands for cron, settingup and configuring jobs.



Creating cron

cron tab files are stored in /var/spool/cron.

This file is accessed only by the root user, whereas theother users cannot access.

User can access this file by using crontab command.



syntax for crontab:

crontab [option]

Option :-e : edit the crontab file.

-l : lists the content of the crontab.

-r : remove the content in crontab.

Creating cron



Root user has

the privilege to

open this file.




Now open

the file.




First field

represents

minutes(0

-59).

Second

field

indicateshours(0-

23)

This files

indicates,

day of themonth (1-

31)

This field

indicates

the month(1-12)

This field

indicates

the day of the

week(0-6)

Command

can be

given inthis field

The above command

gets executed at 13

hours, 34 minutes as

daily basis at same time.

If anyvalues is

not

represented,

we canmention *




The service isrestarted using

service crond

restart.

Chkconfig command

enables the crond

services in runlevel

345 in next boot time.




Automatically

“hello” message

gets displayed in

terminal.




As said before the root user

only has the privilege to

access the file.

The permission isdenied to the normal

user joe when the

user attempts to the

file.




The user can access

the file,

using

crontab –ecommand.




Now open

the file.




The above command

gets executed at 13

hours, 40 minutes as

daily basis at same time.




Crontab –l command

used to display content

of crontab file.




Automatically

“hello joe “message

gets displayed interminal2.




DNS• DNS - Domain naming system.

• DNS service locates and translates domain namesinto corresponding associated IP addresses.

• DNS configuration.

• It requires the following software packages to be

installed.• bind

• Caching-name server

• bind utils



• bind-utils

Service profile

Packages - bind, bind-utils,

caching-nameserver

Configuration files - /etc/named/named.conf

/var/named/named.local

Daemons - named

Port number - 53



Install bind, this

package includes

web page manuals

and documentation

Install bind-utils

which providesmany utilities like

host, dig and

nslookup

Install caching-

name server which

provides a working

named.conf

configuration file

DNS Configuration



configuration file

Open this file for

mentioning the home

directory for DNS.

DNS Configuration



Here DNS home

directory is

/var/named/chroot.

DNS Configuration



View the homedirectory files.

DNS Configuration



Open the

configuration

file named.conf.

DNS Configuration



Now you are

seeing the

contents of

named.conf file.

DNS Configuration



Forward zone mapping

between fully qualified

domain to particular ip

address.

This filecontains the ip

address and

the locations

of all the dot

servers.

DNS Configuration



DNS Configuration



Enter the

forward file

name.

Copy and paste the

forward and reverse

zones and edit them as

follows.

Enter the

domain

name here.

Enter the IP

address inreverse

order.

Enter the

reverse

file name.

DNS Configuration



Save and exit

the file

DNS Configuration



Copying the syntax

file named.local to

example.for andexample.rev.

DNS Configuration



Open the

forward file.

DNS Configuration



Enter the fully

qualified name of

the name server.

It is interpreted as

the name of theoriginating

domain.

Enter the authorised

name server for this

zone.

Enter the fully

qualified name of

host.Enter the last number segment of the host

address in the reverse

zone file.

DNS Configuration



Replace local hostto fully qualified

name using as given

below.

DNS Configuration



Now the localhost is

replaced as

server1.example.com.

DNS Configuration



Enter the ip address for

specified domain name.

Canonical name, is used

to define an alias for ahostname. Set www as

the cname for


DNS Configuration



Open theexample.rev

file.

DNS Configuration



DNS Configuration



Replace localhost toserver1.example.com

using as below.

DNS Configuration



Now the localhost is

replaced by


DNS Configuration



In a PTR record, you can

specify just that last

number segment of the

address.

DNS Configuration



Open theresolve.conf

file.

DNS Configuration



Mention the nameserver

ipaddress and domain

name here.

DNS Configuration



Now named

service is

restarted.

DNS Configuration



Thus the DNS makes it possibleto ping an host by its domain

name by resolving the domain

name into IP address.

DNS Configuration



Thus the DNS makes it possibleto ping an host by its domain



DNS Configuration



dig command shows ip

address of the specified

fully-qualified domain

name

DNS Configuration



name .

Nslookup is a dns

diagnostic tool used toquery a dns server.

Using nslookup you can

identifies nameserver for

particular doamin.


identifies address for

particular FQDN.


identifies FQDN for particular IP address.

DNS Configuration



Thus the DNS makes it possible

to ping an host by its domain



DNS Configuration




to ping an host by its domain



DNS Configuration



In client side open

the /etc/resolv.conf

file.

DNS Configuration



Mention the

nameserver ipaddress

and domain name here.

DNS Configuration




to ping an host by its domainname by resolving the domain


DNS Configuration



It shows the simple

lookup of host,thus itsshow the corresponding

ip address to the

specified fully quailed

domain name.

Using nslookup you canidentifies MX record for

particular domain.


identifies nameserver for

particular domain.

DNS Configuration



Open theforward file.

DNS Configuration



In this file we can add

additional entry MX(mailexchange record ) and its

corresponding ip address

192.168.0.100.

In this file we can add

additional entry station105

machine and its

corresponding ip address

192.168.0.100

DNS Configuration



Open thereverse file.

DNS Configuration



Using nslookup you canidentifies MX record for

particular domain.


identifies address for

particular FQDN.

Using nslookup you canidentifies PTR record for

particular FQDN.

DNS Configuration



Open theconfiguration

file named.conf.

DNS Configuration



Forward zone lists the

name servers outside the

network that should besearched when the

networks name server

fails.

DNS Configuration



Apache Web Server • Apache web server:

• The Apache Web server is a free HTTP (Web)server developed by the Apache Server Project.

• It is a reliable, efficient , and easily extensible WebServer

• Free open source code



Important directories and configuration files

Apache Web Server



Service profile

Packages - httpd

Configurations file - /etc/httpd/conf/httpd.conf

Daemons - httpd

Portnumber - 80



Query a httpd package

whether installed or not

but the screen shows

httpd packages is notinstalled.

Web server configuration




httpd package is

installed using

rpm command.

Now query the

package it show

package is

installed.



Open the httpdconfiguration

file.




You can see the first page file content, we

need to edit the end part

of the, so press shift+G

in command mode thecursor will bottom of

page.




This screen show

end of httpd.conf file.


Copy the last

seven lines .



Paste the copied

lines here .




In virtual host field we

enter ipaddress or fully

qualified domain

address.


Here specify the e-mail

address of the

administrator for the

web server.

Here specify the base

directory from which

html files will be

saved..

Here specify the

hostname for your

server.

Now save and quit

the the httpd.conf file.



After editing the

configuration file The

service httpd is

restarted.




Creating index.html page

and place this file in the/var/www/html/ directory.




Let us create

html file .


After typing save

and quit the file.



Open the mozilla web browser and type the

fully qualified domain

name in address bar and

press enter, it will open

corresponding web page.




To allow only a

particular user to accessour web site we can

add directory session

inside virtualhost

session.


Setting up

/var/www/html/ access

control directive .

Directives that can be

overridden by theentries in an .htaccess

file.



Create .htaccess file

in /var/www/html/

directory and open

the file

.




The authorization realmis given to the client so

the user knows which

username and password

to send.


Type of user authentication for

directory. only Basic

and Digest are currently

implemented.

This file contain list of

users and passwords for user authentication.

Selects theauthenticated users that

can access a directory.




Set the httpd

password for the user joe .



httpd password is

stored in htpasswd

file.




Set full permission for

the htpasswd file to

make sure that the user

has the execute

permission .




To add another user inthe htpasswd file.




Restart the httpd

service.





Enter the fully qualified

domain name in address

bar.



When we access theweb page the mozilla

will prompts for the

username and password.





Enter the username and

the password.




Now you can see theweb page.



Access ControlThe web access can be controlled by using access

control directives such as allow and deny.

Directive Description

deny from hosthost ….

Determines hosts that can access a givendirectory: all, or partial or full domain nameor ip address.

allow from hosthost ….

Determines which hosts can access agiven directory: all, or partial or full domain

name or ip address.



This indicates that wecan access the web page

from any network.




To access the web page

only from the above

specified network.




Virtual host

Virtual hosts allow you to host multiple domains from asingle machine.

Apache supports two different type of virtual hosts.

Name-based virtual hosts

Ip-based virtual hosts



Ip and Named-based Virtual Hosts

IP-based virtual hosts

-Ip-based virtual hosts are used when a singlemachine has several different IP address.

-To run a virtual host on each IP address.

Named-based virtual hosts

-It allow you to host many virtual hosts from asingle IP address.




Here we place two

domains in a single ipaddress and we can

place number of

domains using single

IP address.

Two domains are

used in the name of example and test.com

in a single ip address

192.168.0.20.



An ip address is

mentioned in the

virtualhost field.




The server

fully qualified

domain name is

described here.




described here.

A Directory is created

in the specified path asabove here copy

test.com webpage..




Httpd service is

restarted.




This is the webpage for

the test.com .




This is the webpage for

example.com.




p

Squid

It is the proxy caching server used in Linux.

Handles the request from the local clients for

web access.

It supports all popular internet protocols

including FTP, Gopher ad HTTP.

Proxy Server: Squid



Service profile

Packages - Squid

Configuration files - /etc/squid/squid.conf

Daemons - Squid

Port number - 3128



Squid Configuration

Install the

squid package.

Open the squid

configuration file.



Squid Configuration

This is the default squid

configuration file if we

want to change the

defaults then we can

edit the file.



Squid Configuration

3128 is thehttp port.



Squid Configuration

Search for the aclaccess control list



Create another acl namedthano1 to restrict the web

access by time. Thus here the

web server can be accessed

during 18:30-19:30 only.

Squid Configuration

Search for

http_access in

command mode.The specified range of

IP address are allowed

to access the web server

by assigning them in acl

named thano.



To allow the access lists

thano and thano1

Squid Configuration

This deny other IPaddresses except the IP

addresses mentioned in

access lists



Now restart thesquid

service.

Squid Configuration



To set the proxy

get into the mozila

wizard.

Squid Configuration



Select

preferences to set

the proxy server.

Squid Configuration



And select the

option proxies.

Squid Configuration



Enter the IP address

of the proxy server and the port number.

Squid Configuration



Squid Configuration

Now the time is in between the access time

given in the acl so we

can access web server.



Here you can see that

the access is denied

since the we are notallowed to access the

web server in this time.

Squid Configuration



Apache can provide encrypted communications using the mod_ssl apache module.

To make use of encrypted communications, a client must request the https protocol.

Encryption is based on either the RSA or DSA algorithm.

Apache Encrypted Web Server



Package - mod_ssl

Port number - 443

Certificate - conf/ssl.crt/server.crt

Private key - conf/ssl.key/server.key

Self-signed cert - make testcert

Certificate signature req - make certreq




Query is made to

check whether the

mod_ssl package is

installed. if not,install the packages




To generate the

certificate signature

request.




The self signed certificate

can be installed using the

command

make testcert.




When we restart the

httpd service it will

prompts for the

password.




Open the mozilla browser and type fully

qualified name in the

address bar using https

protocol.




Click here to

view thecertificate.




Here you can view the

certificate informations.




After examining accept the

certificate temporarily or

permanent and then click ok.




You can see a warning

message indicating that

this page can not be

read by a third party.




Now you can access

the web page

securely.




Sendmail:

Red Hat Linux uses Sendmail as its MTA to deliver messages.

It listens for any mail messages received from other hosts andaddress to user on the network host it serves.

It handles the remote messages, determining the host to be sent.

Sendmail Configuration



package - sendmail, sendmail-cf

configuration file - /etc/mail/sendmail.mc

m4 macro config. file - /etc/mail/sendmail.cf

demon service - sendmail

port number - 25(smtp),110(pop)

Sendmail Service Profile




Query is made to

check whether thesendmail package is

installed. if not, install

the packages.



Installing packages

using rpm command.




Open the sendmail

configuration file .




Sendmail

configuration file.




Now we search for the

text 127.0.0.1 .




The cursor finds the

127.0.0.0 (this line isdefault for mail

transferring only for

local host.




The word dnl is added in

the beginning of this line

to comment.


commenting this line

voids to send mail to the

other systems



M4 is a macro languagethat can help to configure

the sendmail.cf file, using

sendmail.mc




Open theVirtusertable file, for

mapping user virtual

domain addresses.




The virutusertableconfiguration helps to

define the domain name

along with fully

qualified domain name.


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