OS lab

Operating System 1

LINUX COMMANDS

Ex:No:1 man,cd,cd .,cd ..,ls,ls-a,pwd commands

Aim: To execute the following commands and write down the results and use of

each Command:(i)man (II)cd (iii)cd. (iv)cd .. (v)ls, ls –a (vi)pwd.

Objectives: i)man :

Used to view the manual pages dealing with particular command.

ii)cd :

Used to change from one directory to another directory. iii)cd . :

Used to display the current working directory.

iv)cd .. : Used to move the previous directory.

v)ls : Used to list out all Files and directory .

vi)ls-a : Used to list all files including the hidden files with dot(.).

vii)pwd : Used to display current working directory.

Syntax used: i. man $man <anyone command name>

ii. cd $cd <directory name>

iii. cd . $cd .

iv.cd .. $cd..

v. ls $ls

Operating System 2

vi. ls-a $ls-a

vii. pwd $pwd

Output: (i)man command:

[su@localhost pgm]$ man cat

CAT(1) User Commands CAT(1)

NAME

cat ΓêÆ concatenate files and print on the standard output

SYNOPSIS

cat [OPTION] [FILE]...

DESCRIPTION

Concatenate FILE(s), or standard input, to standard output.

display TAB characters as ^I

output version information and exit

With no FILE, or when FILE is ΓÇÉ, read standard input.

(ii)cd command:

[su@localhost pgm]$ mkdir java

[su@localhost pgm]$ cd java

[su@localhost java]$

(iii)cd. Command:

[su@localhost pgm]$cd .

[su@localhost pgm]$

(iv)cd ..command:

[su@localhost pgm]$ cd java

[su@localhost java]$ cd ..

[su@localhost pgm]$

Operating System 3

(v)ls,ls –a command:

a)ls: [su@localhost pgm]$ ls

a.out consume.c fifc.c java name.txt upperlower

array deadlock.c intro1.txt maxmin sum.c upperLower

calc fcfs.c intro5.text min.sh upper

[su@localhost pgm]$

b)ls –a: [su@localhost pgm]$ ls -a

. array deadlock.c intro1.txt maxmin sum.c

upperLower

.. calc fcfs.c intro5.text min.sh upper

a.out consume.c fifc.c java name.txt upperlower

(vi)pwd command: [su@localhost pgm]$ pwd

/home/su/pgm

[su@localhost pgm]$

Result:

Thus the above commands were executed successfully.

Operating System 4

Viva Questions:

1. Define Operating System. The operating system is a set of software programs normally

supplied along with the hardware for the efficient use of machine.It

is used to communicate between the hardware and the software.It

act as a bridge between the hardware and the software.

What is meant by Linux operating system? Linux is a clone of Unix operating system.Linux is a complete multi-

userand multitasking operting system

2. What are the different kind of operting systems are available. i) MS-DOS

ii) Windows family

iii) UNIX

iv) LINUX

3. What is the use of Telnet? Telnet is a protocol for logging into remote machines. Through

Telnet, an administrator or another user can access someone else's

computer remotely.

4. Features of Linux: i) Modularity

ii) Multitasking

iii) Multi-User

iv) Communication

v) Transportability

Operating System 5

Ex: no: 2(a) Creating and Deleting a directory

Aim : To make your own subdirectories called uni and linu in your home

directory.Then delete the sub directory called uni and find the

system devices

Objectives:

i)mkdir: Used to create a new directory.

ii)rmdir: Used to remove a directory.

Syntax :

mkdir: $mkdir <directory name>

rmdir: $rmdir <directory name>

Output:

Creating Directory: [su@localhost /]$ cd home

[su@localhost home]$ mkdir uni

[su@localhost home]$ cd uni

[su@localhost uni]$ cd ..

[su@localhost home]$ mkdir linu

[su@localhost home]$ cd linu

[su@localhost linu]$ cd ..

Removing directory: [su@localhost home]$ rmdir uni

[su@localhost home]$ cd uni

-bash: cd: uni: No such file or directory

[su@localhost home]$

Result: Thus the above commands were executed successfully.

Operating System 6

Ex.no:2(b) Explore the file system

Aim: To explore the file system,write what is there in /bin,/usr/bin,/sbin/tmp and

/boot.Find and list the Devices that are available in your system.

Objectives:

i) /bin: This directory holds users’ home directories.

ii) /usr/bin: This directory holds users oriented linux programe.

iii) /sbin/tmp: /sbin holds system files that are usually run automatically

by the linux system.

/tmp is the canonical repository for temporary files and

data.

iv) /boot: It contains files requires to boot the system.

v) Cd: Used to change the directory.

vi) ls: Used to display all files and directories.

vii) Pwd: Print the current working working directory.

Syntax : cd command:

$cd <directory name>

ls command:

$ls

pwd command:

$pwd

Output:

a) /bin [su@localhost /]$ cd bin

[su@localhost bin]$ pwd

/bin

Operating System 7

[su@localhost bin]$ ls

arch cut gawk ls red tar

ash date gettext mail rm tcsh

ash.static dd grep mkdir rmdir touch

aumix-minimal df gtar mknod rpm true

awk dmesg gunzip mktemp rvi umount

basename dnsdomainname gzip more rview uname

bash doexec hostname mount sed

unicode_start

b) /usr/bin [su@localhost\]$cd usr

[su@localhost usr]$cd bin

[su@localhost bin]$ pwd

/usr/bin

[su@localhost bin]$ls

kmenuedit ttfprint

kmessedwords ttindex

kmid ttmkfdir

kmidi tty

kmines tunctl

kminspector tuxracer

c) /sbin/tmp: [su@localhost sbin]$ cd tmp

[su@localhost tmp]$ pwd

/sbin/tmp

[su@localhost tmp]$ ls

orbit-root scrollkeeper-tempfile.0 ssh-XXhjLRpu ssh-XXrRZwNw

ssh-XxzmVzhi

d) /boot [su@localhost /]$ cd boot

[su@localhost boot]$ pwd

/boot

[su@localhost boot]$ ls

boot.b module-info-2.4.18-14smp

chain.b module-info-2.4.18-14uml

config-2.4.18-14 os2_d.b

config-2.4.18-14debug System.map

Operating System 8

To find the System devices: [Stewaugh@localhost dev]$ cd /

[Stewaugh@localhost /]$ ls

bin dev home lib misc net proc sbin tmp var

boot etc initrd lost+found mnt opt root tftpboot usr

[Stewaugh@localhost /]$ cd dev

[Stewaugh@localhost dev]$ ls

OUTPUT:

hdl20 ptyv7 sdcc14 sdep3 sdhb6 sgn urandom

hdl21 ptyv8 sdcc15 sdep4 sdhb7 sgo usb

hdl22 ptyv9 sdcc2 sdep5 sdhb8 sgp vbi

hdl23 ptyva sdcc3 sdep6 sdhb9 shm vbi0

hdl24 ptyvb sdcc4 sdep7 sdhc sjcd vbi1

hdl25 ptyvc sdcc5 sdep8 sdhc1 smouse vbi2

hdl26 ptyvd sdcc6 sdep9 sdhc10 smpte0 vbi3

hdl27 ptyve sdcc7 sdeq sdhc11 smpte1 vcs

hdl28 ptyvf sdcc8 sdeq1 sdhc12 smpte2 vcs1

hdl29 ptyw0 sdcc9 sdeq10 sdhc13 smpte3 vcs10

hdl3 ptyw1 sdcd sdeq11 sdhc14 sndstat vcs11

hdl30 ptyw2 sdcd1 sdeq12 sdhc15 socksys vcs12

hdl31 ptyw3 sdcd10 sdeq13 sdhc2 sonycd vcs13

hdl32 ptyw4 sdcd11 sdeq14 sdhc3 spx vcs14

Result: Thus the files are explored using ls,cd and pwd commands successfully.

Operating System 9

Viva Questions:

1. What are the commands available to display a certain number of lines

on the screen? a) head : To display the specified number of lines from the

beginning of a file.

head <option> <file name>

Eg: head -2 flower.txt

b) tail: To display the specified number of lines from the end of a

file.

tail <option> <file name>

2. Define Wildcard Characters. Use special characters in the command instead of actual file

names.These special characters are calles as wildcard characters.

3. What are the filtes available in Linux? i) cat

ii) grep

iii) wc

iv) tr

v) cut

4. grep: The grep filter searches a file for a specified patten os charcters

and displays all the lines that contain the patternThe patten that is

searched for is referred to as a regular expression.The grep filter

cannot be used without specifying a regular expression.

grep regular_expression <file name>

Character Purpose

* Matches one or a string of charactes.

? Matches exactely one character.

[ ] Matches exactly one of a specified character.

Operating System 10

Ex.No:3(a) Creating and Copying a File from one directory

to other Directory

Aim: To create and copy a file from one directory to another directory.

Objectives:

i) Cat > : Used to create a new file.

ii) Cat: Used to view the contents of a file.

iii) Cp: Used to copy the file from source to destination.

Syntax:

a) Cat >: $ cat > <file name>

b) Cat: $ cat <file name>

c) cp: $ cp –r <source directory name> <destination directory name>

Output: Creating a file:

[su@localhost su]$ cat >intro4.text

Hello I am the student of computer branch

[8]+ Stopped cat >intro4.text

Viewing a file:

[su@localhost su]$ cat intro4.text


[su@localhost su]$ pwd

/home/su/su

Operating System 11

Copying a file:

[su@localhost su]$ cp intro4.text /home/su/pgm/intro5.text

[su@localhost su]$ cd ..

[su@localhost su]$ cd pgm

[su@localhost pgm]$ cat intro5.text


[su@localhost gm]$

Result: Thus the above command were executed successfully.

Operating System 12

Ex.No:3(b) Changing the file permission

Aim: To change the file permission using different commands.

Objectives:

chmod: Used to change the file permission.

Syntax: I)Chmod (Using symbolic mode):

$chmod <group> <operation> <mode> <filename>

Where

Group Operation mode

u-user + assign permission r –read

g-group - remove permission w-write

o-other = assign absolute x-execute

a-all

ii) chmod (using absolute mode):

$chmod octalnumber filename

Where

Octalnumber 4 - read permission

2 - write permission

1 - execute permission

6 - read write permission

Operating System 13

Output:

Chmod (Using symbolic mode):

[su@localhost pgm]$ ls -l intro.text

-rw-rw-r-- 1 su su 42 Apr 4 12:03 intro.text

[su@localhost pgm]$ chmod u+rwx intro.text


-rwxrw-r-- 1 su su 42 Apr 4 12:03 intro.text

[su@localhost pgm]$ chmod g+wx intro.text


-rwxrwxr-- 1 su su 42 Apr 4 12:03 intro.text

[su@localhost pgm]$ chmod o-r intro.text


-rwxrwx--- 1 su su 42 Apr 4 12:03 intro.text

Chmod (Using absolute mode):

[su@localhost pgm]$ chmod 641 intro.text


-rw-r----x 1 su su 42 Apr 4 12:03 intro.text



---------- 1 su su 42 Apr 4 12:03 intro.text



--w-rw---x 1 su su 42 Apr 4 12:03 intro.text

Result: Thus the above commands to change the file permission were executed

successfully.

Operating System 14

Ex.No:3(c) Usage of Find command

Aim: To display the name of all files in the home directory using find command.

Objectives:

find: Used to display all files in the home directory.

Syntax:

I)find $find

$find –name ‘*’ –size +<file size in kilobyte (k)>

Where

* denotes to search all the files.

Output: [su@localhost home]$ find

./su/su/intro3.text

./su/su/intro.text

./su/su/intro4.text

./su/su/lock.c

./su/su/a

./su/su/deadlockavoi.c

./su/su/deadlock.c

./su/su/deadlockavoidance

./su/su/deadlockavoidance.c

./su/.viminfz.tmp

[su@localhost home]$ find -name '*' -size +500k

[su@localhost home]$ find -name '*' -size +10k

./lost+found

./pgm/a.out

./suja/pg1

./suja/pg1~

./suja/OS lab.sxw

./a.out

./mbox

[suja@localhost suja]$

Operating System 15

Result: Thus the find command was successfully executed and display all

files in the home directory.

Viva Questions

1. clear: It is used to Clears the terminal screen.

Syntax:

$ clear

2. cmp: Compares two files, reporting all discrepancies

Syntax:

$cmp file1 file2

3. diff:

Compares two files, reporting all discrepancies

Syntax:

$diff file1 file2

Operating System 16

Ex:no:4(a) Use of finger and who commands

Aim: To use finger or who to get a list of users on the machine.

Objectives:

i)finger: It provides you with more complete information about the users

who are logged in.

ii)who: To see who is using the system.

Syntax: i.Finger command:

$finger (or) $finger <user name>

ii.who command:

$who

Output:

Finger command: [su@localhost pgm]$ finger

Login Name Tty Idle Login Time Office Office Phone

root root *:0 Apr 4 09:22

su sumasu pts/1 Apr 4 09:52 (sys7.ceserver.local)

[su@localhost home]$ finger su

Login: su Name: sumasuja

Directory: /home/su Shell: /bin/bash

On since Thu Apr 17 09:06 (IST) on pts/1 from sys7.ceserver.local

No mail.

No Plan.

Who command: [su@localhost pgm]$ who

root :0 Apr 4 09:22

su pts/1 Apr 4 09:52 (sys7.ceserver.local)

[su@localhost su]$ who am i

su pts/0 Apr 19 11:49 (sys7.ceserver.local)

[su@localhost pgm]$

Result: Thus the who and finger commands were executed successfully.

Operating System 17

Ex: no: 4(b) Add different Users and set their Passwords &

Permissions Aim: To add a different users and set their passwords and change their

permissions.

Objectives:

i) adduser: To add a new user.

ii) Passwd: To set the password in the existing user.

iii) Chmod : Define the permission to the user.

Syntax: i) Add a new user:

$ useradd <user name>

ii) Change password:

$ passwd <user name>

iii) Define Permissions:

a)Chmod (Using symbolic mode):

$chmod <group> <operation> <mode>

<username>

Group Operation mode

u-user + assign permission r –read

g-group - remove permission w-write

o-other = assign absolute x-execute

a-all

b)chmod (using absolute mode):

$chmod <octalnumber>< filename>

Where

Octalnumber 4 - read permission

2 - write permission

1 - execute permission

6 - read write permission

Operating System 18

Output Add a new user:

[root@localhost root]# useradd kala

Change password:

[root @localhost root]# passwd kala

Changing password

New password:

BAD password: it is based on a dictionary word

Retype new password:

Passwd: all authentication token updated successfully.

Define Permission:

[root @localhost home]#ls –l

drwxrwxrwx 3 admin admin 4096 Apr 2 12:17

admin

drwxrwxrwx 3 ce2850348 users 4096 Apr 3 12:41

ce2850348


ce2850325

drwx------ 3 jj jj 4096 Apr 22

12:52 jj

drwx------ 3 kala kala 4096 Apr 17

16:52 kala

[root @localhost home]#chmod g+rx kala

[root @localhost home]ls –l


admin


ce2850348


ce2850325

drwx------ 3 jj jj 4096 Apr 22

12:52 jj

drwxr-x---- 3 kala kala 4096 Apr 17

16:52 kala

[root @localhost home]#chmod 246 kala

[root @localhost home]#ls -l


admin

Operating System 19


ce2850348


ce2850325

drwx------ 3 jj jj 4096 Apr 22

12:52 jj

-w-r—rw- 3 kala kala 4096 Apr 17 16:52

kala

[root @localhost home]#

Result: Thus the above commands to add a new user, chage therir password and

change their permission were verified successfully.

Operating System 20

Ex: no: 4(c) Delete the existing user

Aim: To delete a user that have already exist.

Objectives:

i) Userdel: Used to delete a user.

Syntax: $ userdel < user name >

Output: [root@localhost root]# userdel kala

Result: Thus the above command to delete the existing user was verified

successfully.

Viva Questions:

1. Free: Displays the amount of used and free system memory.

Syntax:

$free

2. Clear: Clears the terminal screen.

Syntax:

$clear

3. W: Prints the current system workers.

Syntax:

$w

Operating System 21

Ex.No:5(a)Download files from remote machine to local host

Aim: To try to access your account available at a remote machine and download

a file from remote machine to local host.

Objective:

i) cp : To copy the file from one user to another.

ii) Cat: To view the content of the copied file.

Syntax:

cp: $cp –r <source file name> <destination file name>

cat: $cat <file name>

Output: [su@localhost home]$ cp -r /home/intro hh

[su@localhost home]$ cat hh

Welcome to M.S.P.V.L Polytechnic college.

Result: Thus the above commands were executed successfully.

Operating System 22

Ex.No:5(b) Create a Cron job that sends you a message after

every 5minutes

Aim: To create a cron job that sends you a message after every 5 minutes.

Objectives: i) Crontab –e:

To create a new crontab file.

ii) Crontab –l: To display all the cron jobs.

iii) Crontab –r: To remove the cron job.

Syntax:

Create a crontab file: $crontab –e

Display the cron job: $crontab –l

Remove the cron job: $crontab –r

Output [su@localhost su]$ crontab -e

[su@localhost su]$ crontab -l

# DO NOT EDIT THIS FILE - edit the master and reinstall.

# (/tmp/crontab.2392 installed on Mon Apr 21 11:12:09 2008)

# (Cron version -- $Id: crontab.c,v 2.13 1994/01/17 03:20:37

vixie Exp $)

*/2 * * * * echo "Hello"

[su@localhost su]$ mail

Mail version 8.1 6/6/93. Type ? for help.

"/var/spool/mail/su": 30 messages 30 new

>N 1 [email protected] Mon Apr 21 11:16 20/803 "Cron

<su@localhost>"

N 2 [email protected] Mon Apr 21 11:18 20/803 "Cron

<su@localhost>"

&

Message 1:

Operating System 23

From [email protected] Mon Apr 21 11:16:32 2008

Date: Mon, 21 Apr 2008 11:16:01 +0530

From: [email protected] (Cron Daemon)

To: [email protected]

Subject: Cron <su@localhost> echo "Hello"

X-Cron-Env: <SHELL=/bin/sh>

X-Cron-Env: <HOME=/home/su>

X-Cron-Env: <PATH=/usr/bin:/bin>

X-Cron-Env: <LOGNAME=su>

Hello

&

Message 2:

From [email protected] Mon Apr 21 11:18:32 2008

Date: Mon, 21 Apr 2008 11:21:00 +0530

From: [email protected] (Cron Daemon)

To: [email protected]

Subject: Cron <su@localhost> echo "Hello"

X-Cron-Env: <SHELL=/bin/sh>

X-Cron-Env: <HOME=/home/su>

X-Cron-Env: <PATH=/usr/bin:/bin>

X-Cron-Env: <LOGNAME=su>

Hello

&

At EOF

[su@localhost su]$ crontab –r

[su@localhost su]$ crontab -l

no crontab for su

Result:

Thus the above command to create a cron job that sends a mesage after

every 5 minutes.

Operating System 24

Ex.No:5(c) Use of wall command

Aim: To write a message to inform all users that “they should shut down their

machine after completing the lab exercise”.

Objectives:

Wall: To broadcast a message to all users connected to the

server.

Syntax:

$wall <Type your message here>

Press Ctrl+d

Output: [su@localhost su]$ wall

They should shut down their machine after completing the lab

exercise.

[su@localhost su]$

Broadcast message from su (pts/0) (Mon Apr 21 15:01:22 2008):

They should shut down their machine after completing the lab

exercise.

Result:

Thus the program to broadcast a message to all users using wall

command executed successfully.

Operating System 25

SHELL PROGRAMS Ex: No: 6(a) Factorial of a given number

Aim: To write a program to find the factorial of a given number

Procedure: 1) Create a new vi editor file.

2) Get the input number.

3) Set i=1 and fact=i

4) Check i less than n the fact=fact*i

5) Increment the variable i.

6) Repeat the steps up to this condition false(ie i<n)

7) Print the result.

Program: #!bin/bash

echo "Enter the number"

read n

i=1

fact=1

while [ $i -le $n ]

do

((fact=$fact*$i))

((i=$i + 1))

done

echo "Factorial of $n is: $fact"

Output: [root@localhost root]# bash factor

Enter the number

6

Factorial of 6 is :720

Result: Thus the program to find the factorial of the given number was executed

successfully.

Operating System 26

Ex.No:6(b) Sum of Odd/Even numbers from M to N

Aim: Write a program to find the sum of odd/even numbers from M to N.


2) Get the value of n and m

3) Initialize k=0 and p=0.

4) Find the modulo of the input series.

5) If the modulo output is zero the given number is odd else the

number is even

6) Find the sum of odd and even numbers separately.


Program: #!bin/bash

echo "Enter the value of m"

read m

echo "Enter the value of n"

read n

k=0

p=0

while [ $m -le $n ]

do

((t=m%2))

if [ $t -eq 0 ]

then ((p=p+m))

else

((k=k+m))

fi

((m=m+1))

done

echo "The sum of odd numbers are $k"

echo "The sum of even numbers are $p"

Operating System 27

Output: [root@localhost root]# bash pg2

Enter the value of m

1

Enter the value of n

10

The sums of odd numbers are 25

The sums of even numbers are 30

Result: Thus the program to find the odd or even of the given number was

executed successfully

Operating System 28

Viva Questions

1. What is meant by Text Editors? A Text Editor is a program that enables you to create and modify

text files. It provides a screen with a fixed line length and line

numbers. You can type text line by line, navigate through the

documents y using different commands and save the document.

2. What are Editors available with Linux? i) vi Editor

ii) vim Editor

iii) emacs Editor

iv) ed Editor

v) red Editor

vi) joe Editor

vii) pico Editor

3. What is meant by vi Editor? The vi Editor is a visual Editor used to create and edit text

files,documents,and programs.

The following command is used to invoke the vi Editor

Vi Filename <Enter>

4. Commands used in the vi Editor

Commands Action

H Moves the coucor to the previous character.

L Moves the cursor to the next character.

K Moves the cursor to the line above the

current line.

J Moves the cursor to the line above the

current line.

X Deletes the character at the current cursor

position.

:wq<Enter> Saves all the changes and quits the vi

Editor.

:w<Enter> Saves the File.

Operating System 29

:q<Enter> Quits without saving File.

:e <File Name> <Enter> Opens the specified File.

:w! <File Name> <Enter> Forcefully writes to the specified File.

:! <command Name>

<Enter> Executes a shell command.

:r <File name><Enter> Reads and Inserts the contents of the file

after the current file.

5. Insert and Replce commands:

Commands Action

A Enables you to append text after the current

character.

A Enables you to append text at the end of the file.

I Enables you to insert text before the current

character.

I Enables you to insert text at the end of the file.

O Inserts a blank line below the current line, and

allows you to inser text.

O Inserts a blank line below the current line, and

allows you to inser text.

Operating System 30

Ex: No:7(a) Find the greatest of given three numbers

Aim: Write a program to find greatest of given three numbers.


2) Get the 3 input numbers.

3) Get the value for three variables.

4) Find the greatest value among them, using greater than(-gt)


Program: #!bin/bash

echo "Enter the 3 elements one by one:"

read a

read b

read c

if [ $a -gt $b -a $a -gt $c ]

then

echo "$a is greater"

elif [ $b -gt $c ]

then

echo "$b is greater"

else

echo "$c is greater"

fi

Output: Enter the 3 elements one by one:

10

20

100

100 is greater

Result: Thus the program to find the greatest of the given number was executed

successfully

Operating System 31

Ex:No:7(b) Find out the max and min number of a

given series

Aim: Write a program to find out the maximum and minimum number of

the given series.


2) Get the number of elements in the array.

3) Get the elements one by one.

4) Check the numbers one by one

5) Find the maximum and minimum in the given array.


Program: #!bin/bash

echo "Enter the no of elements in the array:"

read n

echo "Enter the elements one by one:"

i=0

while [ $i -lt $n ]

do

read array[$i]

let i++

done

len=${#array[*]}

echo "The array has $len members They are"

i=0

while [ $i -lt $len ]

do

echo "$i:${array[$i]}"

let i++

done

i=0

j=1

min=${array[$i]}

max=${array[$i]}

while [ $j -lt $len ]

Operating System 32

do

sec=${array[$j]}

if [ $min -gt $sec ]

then

min=$sec

elif [ $max -lt $sec ]

then

max=$sec

fi

let j++

done

echo "Minimum=$min"

echo "Maximum=$max"

Output: [su@localhost pgm]$ bash maxmin

Enter the no of elements in the array:

6

Enter the elements one by one:

4

78

3

56

789

45

The array has 6 members they are

0:4

1:78

2:3

3:56

4:789

5:45

Minimum=3

Maximum=789

Result: Thus the above program to find the maximum and minimum in the given

series was executed successfully.

Operating System 33

Viva Questions

1. What is the purpose of shell scripts? The shell is an intermediary program, which interprets the

commands that are typed at the command prompt. The shell

translates the commands that you type into commands that are

understood by the kernel. The shell acts as an interface between

the users and the kernel and eliminates the need for a programmer

to communicate directly with the kernal.

2. What are the steps for shell script process. i) When ou log on, the shell displays the Linux Prompt, indicating

that it is ready to execute commands.

ii) When you give a command, the shell performs the follwoing

tasks.

a) Reads the command

b) Searches for and locates the file,which has the same name

as the command, in the directories containing utilities.

c) Loads the appropriate utility into memory.

d) Executes the utility.

3. What are the commands are available to execute the script file. i) At the command prompt ,type

$ bash <File Name>

If there is an eror in the first line of the shell script that you

are executing, you might receive the “No such file or

directory”error message. To resolve the problem type the

where is bash command to locate the path of the bash

program, and use the path in the shell scirpt.

ii) At the command prompt ,type

$ chmod u+x <File Name>

$ ./<File Name>

Operating System 34

Ex.No:8(a) Palindrome Checking

Aim: Write a program to convert the lowercase characters into uppercase and

uppercase characters into lowercase character of a given string.


2) Read the input string.

3) Find the length of the given string.

4) Separate the string character by character using substring function.

5) Reverse the string and store the string temporarily

6) compare the reversed string with input string.

7) If it is equal then print the given string is palindrome otherwise

print not palindrome

Program:

#!bin/bash

echo "Enter the string:"

read str

len=${#str}

k=$len-1

i=0

flag=1

while [ $i -le $((len / 2))

do

s1=${str:$i:1}

s2=${str:$k-i:1}

if [ $s1 != $s2 ]

then

flag=0

fi

let i++

done

if [ $flag -eq 1 ]

then

echo "Palindrome"

Operating System 35

else

echo "Not Palindrome"

fi

Output: Enter the string:

AMMA

Palindrome

Enter the string:

Lecturer

Not Palindrome

Result: Thus the above program to covert the upper case into lower case

and vice versa were executed successfully.

Operating System 36

Ex.No:8(b) Find the LENGTH of given string

Aim: To find the length of given string.



3) Find the length and substring of the given string.

4) Initialize the count value (i.e.) count=0.

5) If the substring character is match with any vowels character then

increase the count value.

6) Print the count value

Program: #!bin/bash

echo "Enter the string "

read str

len=${#str}

echo "$len"

Output:

[Stewaugh@localhost suja]$ bash length

Enter the string

Stewaugh

8

Result: Thus the above program to find the number of vowels present in a given

string was executed successfully.

Operating System 37

Viva Questions

1. List out the Arithmetic test operators.

Option Meaning

‐eq Equal to

‐ne Not eaual to

‐gt Greater than

‐ge Greater than or equal to

‐lt Less than

‐le Less than or equal to

Operating System 38

Ex.No:9 Develop a Calculator Application

Aim: To develop a calculator application.

Procedure: 1) Create a new file.

2) Read the operands.

3) Select any one operation from the list.

4) Perform the operation.


Program: # Implementation of Calculator application

#!bin/bash

j=1

while [ $j -eq 1 ]

do

echo "Enter the First Operand;"

read f1

echo "Enter the second operand:"

read f2

echo "1-> Addition"

echo "2-> Subtraction"

echo "3-> Multiplication"

echo "4-> Division"

echo "Enter your choice"

read n

case "$n" in

1)

echo "Addition"

f3=$((f1+f2))

echo "The result is:$f3"

;;

2)

echo "Subtraction"

let "f4=$f1 - $f2"


;;

3)

Operating System 39

echo "Multiplication"

let "f5=$f1 * $f2"


;;

4)

echo "Division"

let "f6=$f1 / $f2"


;;

esac

echo "Do you want to continue(press:1 otherwise press any key to

quit)"

read j

done

Output: [su@localhost su]$ bash u

Enter the First Operand;

23

Enter the second operand:

23

1-> Addition

2-> Subtraction

3-> Multiplication

4-> Division

Enter your choice

1

Addition

The result is:46

Do you want to continue(press:1 otherwise press any key to quit)

1


20


2

1-> Addition

2-> Subtraction

3-> Multiplication

4-> Division

Operating System 40

Enter your choice

2

Subtraction

The result is:18


1


24


2

1-> Addition

2-> Subtraction

3-> Multiplication

4-> Division

Enter your choice

3

Multiplication

The result is:48


1


24


12

1-> Addition

2-> Subtraction

3-> Multiplication

4-> Division

Enter your choice

4

Division

The result is:2


q

[su@localhost su]$

Result: Thus the above program to develop a calculator application was

executed successfully.

Operating System 41

Viva Questions

1. Define a loop. A loop is a block of code that repeats a set of commands based on

the value of the specified condition.

2. Synatx for Looping Statements.

While: While <condition>

do

<command(s)>

done

until: While <condition>

do

<command(s)>

done

for: for variable_name in <list_of_values>

do

<command(s)>

done

Operating System 42

C- PROGRAMS Ex.No:10 Implement Deadlock Avoidance Algorithm

using C Language

Aim: To implement deadlock avoidance algorithm using c language.

Procedure: 1) Create a new file with .c extension.

2) Get the total number of processess, total number of resources

and requesting processes.

3) Check whether the requested resources available or not.

4) If it is available then allocate the resources and it consider as a

safe state.

5) Else the particular process is not secure.

Program: #include<stdio.h>

#include<stdlib.h>

main()

{

const int max = 10; //max multiplicity

int i, j, z; //counters

int P, L, N; //P=processes, L= FREE, N= maximum multiplity

int A[10], R[10], M[10]; //A= allocates, R=request, M= maximum

requests

int RS[10]; //RS= folowing request

int LS[10]; //free resurces after the i-allocation

int CP[10]={0}; //CP= processes classification

int MAX[10];

int lim; //max limit

do

{

printf("\nHOW MANY PROCESSES DO YOU WANT? ");

scanf("%d",&P);

} while(P>max);

printf("\nENTER THE TOTAL NO OF RESOURCES: ");

scanf("%d",&N);

Operating System 43

for(i=1;i<=P;i++)

{

printf("\nHOW MANY UNIT HAS THE P%d PROCESS?",i);

scanf("%d",&A[i]);

printf("\nHOW MANY UNIT REQUEST THE P%d

PROCESS?",i);

scanf("%d",&R[i]);

printf("\nWHAT IS THE MAX NUMBER OF UNITS OF THE

P%d PROCESS?",i);

scanf("%d",&M[i]);

printf("\n\n");

}

L=N;

for(i=1; i<=P; i++)

L-=A[i]; //nuber of units still idle

for(i=1; i<=P; i++)

{

if(R[i]<=L) //is secure?

{

RS[i]=M[i]-A[i]-R[i]; //next request

LS[i]=L-R[i]; //idle resuorces after the allocation

}

else //isn't secure

{

LS[i]=-1;

}

}

for(i=1; i<=P; i++)

MAX[i]=-1; //or 0???

z=1;

for(i=1; i<=P; i++)

{

if(i==1)

{

for(j=1; j<=P; j++)

{

if(LS[j]>=MAX[z])

{

Operating System 44

MAX[z]=LS[j];

CP[z]=j;

lim=MAX[z];

}

}

}

else

{

for(j=1; j<=P; j++)

{

if((LS[j]>=MAX[z])&&(LS[j]<lim))

{

MAX[z]=LS[j];

CP[z]=j;

lim=MAX[z];

}

}

}

z++;

}

for(i=1; i<=P; i++)

{

if(LS[i]!=-1)

printf("\nTHE PROCESS %d IS THE %dstCHOICE\n",i,CP[i]);

else

printf("THE PROCESS %d IS NOT SECURE",i);

}

}

Output: [su@localhost su]$ cc deadlockavoidance.c

[su@localhost su]$ ./a.out

HOW MANY PROCESSES DO YOU WANT? 2

ENTER THE TOTAL NO OF RESOURCES: 10

HOW MANY UNIT HAS THE P1 PROCESS?3

HOW MANY UNIT REQUEST THE P1 PROCESS?2

WHAT IS THE MAX NUMBER OF UNITS OF THE P1 PROCESS?6

Operating System 45

HOW MANY UNIT HAS THE P2 PROCESS?4

HOW MANY UNIT REQUEST THE P2 PROCESS?7

WHAT IS THE MAX NUMBER OF UNITS OF THE P2 PROCESS?8

THE PROCESS 1 IS THE 1stCHOICE

THE PROCESS 2 IS NOT SECURE

[su@localhost su]$

Result: Thus the above C program to implement the deadlock avoidance

was executed successfully.

Viva Questions:

1. Define deadlock? In a multiprogramming environment, several processes may compete for a

finite number of resources. A process request resources; if the resources are not

available at that time, the process enters a wait state. Waiting processes may

never again change state because the resources they have requested are held by

other waiting processess.This situation is called deadlock.

(Or) Two processes would stay blocked forever and no more work would ever

be done. This situation is called deadlock.

2. What are the algorithms are available to implement the Deadlock

avoidance? a) Safe state Algorithm.

b) Resource Allocation Graph algorithm.

c) Bankers algorithm.

i) Safety algorithm.

ii) Resource-Request Algorithm.

Operating System 46

Ex.No:11 Implement Multithreading Concepts

Aim: To implement multithreading concept using C language.

Procedure: 1. Create a new file with .c extension.

2. Define the three threads.

3. Each thread is responsible for separate process. All the three

threads workout simultaneously.

4. Display the output.

5. Stop the program.

Program: #include <pthread.h>

#include <stdio.h>

#define NUM_THREADS 3

void *BusyWork(void *null)

{

int i;

double result=0.0;

for (i=0; i<1000000; i++)

{

result = result + (double)random();

}

printf("result = %e\n",result);

pthread_exit ((void *) 0);

}

int main (int argc, char *argv[])

{

pthread_t thread[NUM_THREADS];

pthread_attr_t attr;

int rc, t;

void *status;

/* Initialize and set thread detached attribute */

pthread_attr_init(&attr);

pthread_attr_setdetachstate(&attr,PTHREAD_CREATE_JOINABLE);

Operating System 47

for(t=0; t<NUM_THREADS; t++)

{

printf("Creating thread %d\n", t);

rc = pthread_create(&thread[t], &attr, BusyWork,

NULL);

if (rc)

{

printf("ERROR; return code from

thread_create()is %d\n", rc);

exit(-1);

}

}

/* Free attribute and wait for the other threads */

pthread_attr_destroy(&attr);

for(t=0; t<NUM_THREADS; t++)

{

rc = pthread_join(thread[t], &status);

if (rc)

{

printf("ERROR; return code from

pthread_join()is %d\n", rc);

exit(-1);

}

printf("Completed join with thread %d status=

%ld\n",t,(long)status);

}

pthread_exit(NULL);

}

Output: [su@localhost su]$ cc -pthread example2.c

[su@localhost su]$ ./a.out

Creating thread 0

Creating thread 1

Creating thread 2

result = 1.073708e+15

Completed join with thread 0 status= 0

result = 1.073647e+15


Operating System 48

result = 1.073621e+15


[su@localhost su]$

Result: Thus the above program to implement the multithreading concept

was executed successfully.

Viva Questions:

1. What is meant by thread? Thread represents a software approach to improve the performance of

operating system by reducing the overhead of process switching. It is a light

weight process with a reduced state. State reduction is achieved by having a

group of related threads share other resources such as memory and files.

2. What is the use of pthread.h header file? Pthread.h header file must include implementing threading concepts.

3. What is meant by multithreading? Multiple threads of execution within a single process are called

multithreading.

4. List out the benefits of thread compare to the processes a) Less time to create a new thread than a process, because the

newly created thread uses the current process address space.

b) Less time to terminate a thread than a process.

c) Less time to switch between two threads within the same

process, partly because the newly created thread uses the

current process address space.

d) Less communication overheads -- communicating between the

threads of one process is simple because the threads share

everything: address space, in particular. So, data produced by

one thread is immediately available to all the other threads.

Operating System 49

Ex.No:12 First Come First Served (FCFS) Scheduling

Aim: To implement FCFS scheduling algorithm and print the average waiting

time and average turnaround time.

Procedure: 1. Create a new file with .c extension.

2. Get the number of process, process name, burst time and

arrival time of every process.

3. The Gantt chart value is calculated.

4. Calculate average waiting time and average turnaround time.

5. Stop the program.

Program: #include<stdio.h>

#include<string.h>

int main()

{

Int n,i,j,temp,exe[15],arrival[15],wait[15],tat[15],

timearray[15];

float twt=0,ttat=0,avgwt=0,avgtat=0;

char pid[15][15],tname[15],namearray[15][15];

printf("\n Enter the number of process:");

scanf("%d",&n);

for(i=1;i<=n;i++)

{

printf("\nEnter the process name:");

scanf("%s",&pid[i]);

printf("\nEnter the execution time:");

scanf("%d",&exe[i]);

printf("\n Enter the arrival time:");

scanf("%d",&arrival[i]);

}

for(i=1;i<=n;i++)

{

for(j=i;j<=n;j++)

{

if(arrival[i]>arrival[j])

{

Operating System 50

strcpy(tname,pid[i]);

strcpy(pid[i],pid[j]);

strcpy(pid[j],tname);

temp=exe[i];

exe[i]=exe[j];

exe[j]=temp;

temp=arrival[i];

arrival[i]=arrival[j];

arrival[j]=temp;

}

}

}

timearray[0]=0;

for(i=1,j=1;i<=n;i++,j++)

{

if(arrival[i]>timearray[j-1])

{

timearray[j]=arrival[i];

strcpy(namearray[j],"idle");

i=i-1;

}

else

{

timearray[j]=timearray[j-1]+exe[i];

strcpy(namearray[j],pid[i]);

}

}

for(i=1,j=1;i<=n;i++,j++)

{

if(strcmp(namearray[j],"idle")==0)

{

i=i-1;

}

else

{

wait[i]=timearray[j-1]-arrival[i];

tat[i]=timearray[j]-arrival[i];

twt=twt+wait[i];

Operating System 51

ttat=ttat+tat[i];

}

}

avgwt=twt/n;

avgtat=ttat/n;

printf("\n Name arrival Execution Waiting

Turnaround Time\n");

for(i=1,j=1;i<=n;i++,j++)

{

if(strcmp(namearray[j],"idle")==0)

{

i=i-1;

}

else

{

printf("\n%s",namearray[j]);

printf("\t%d",arrival[i]);

printf(" %d to %d",timearray[j-

1],timearray[j]);

printf(" %d",wait[i]);

printf(" %d",tat[i]);

printf("\n");

}

}

printf("\n Average waiting time:%f",avgwt);

printf("\n Average turnaround time:%f\n",avgtat);

return(0);

}

Output: [su@localhost pgm]$ cc fifc.c

[su@localhost pgm]$ ./a.out

Enter the number of process:3

Enter the process name:a

Enter the execution time:5

Operating System 52

Enter the arrival time:1

Enter the process name:b



Enter the process name:c



Name arrival Execution Waiting Turnaround Time

a 1 1 to 6 0 5

b 3 6 to 12 3 9

c 4 12 to 19 8 15

Average waiting time:3.666667

Average turnaround time:9.666667

[su@localhost pgm]$

Result: Thus the above program to implement FCFS Scheduling Algorithm was

executed successfully.

Viva Questions:

1. What is meant by First Come First Served? First-Come-First-Served algorithm is the simplest scheduling algorithm.

Processes are dispatched according to their arrival time on the ready

queue. Being a no preemptive discipline, once a process has a CPU, it runs

to completion.

Operating System 53

EXTRA PROGRAMS 1. Find whether a given number is Prime or not

Aim: Write a program to find whether a given number is prime number or

not.


2) Get the input number.

3) Initially set flag=0

4) Divide the given number by 2.

5) Find the modulo of the dividing output.

6) If the modulo output is zero then set the flag=1.

7) If the flag value is 1 then the given number is a prime number

otherwise the number is not a prime number.


Program: #!bin/bash

echo "Enter the number"

read n

j=2

flag=0

((y=$n / 2))

while [ $j -le $y ]

do

((s=$n % $j ))

if [ $s -eq 0 ]

then flag=1

fi

((j=$j+1))

done

if [ $flag -eq 0 ]

then

echo "$n is a prime number"

else

echo "$n is not a prime number"

fi

Operating System 54

Output: [su@localhost su]$ bash prime

Enter the number

123

123 is not a prime number

[su@localhost su]$ bash prime

Enter the number

11

11 is a prime number

[su@localhost su]$

Operating System 55

2. String Conversion

Aim: Write a program to convert the lowercase characters into uppercase and

uppercase characters into lowercase character of a given string.



3) Find the length of the given string.

4) Separate the string character by character using substring function.

5) Check whether the character is upper or lower.

6) If the character is upper covert to lower case character otherwise

converted into uppercase.

7) Print the converted string.

Program: #!bin/bash

echo "Enter the string"

read str

array=(a b c d e f g h i j k l m n o p q r s t u v w x y z)

a1=${#array[*]}

arr=(A B C D E F G H I J K L M N O P Q R S T U V W X Y Z)

a2=${#arr}

st=${#str}

echo "The string length is:$st"

i=0

j=1

k=0

f=0

while [ $k -lt $st ]

do

ss=${str:$i:$j}

while [ $f -lt $a1 ]

do

if [ $ss = ${array[$f]} ]

then

str=${str/$ss/${arr[$f]}}

elif [ $ss = ${arr[$f]} ]

then

Operating System 56

str=${str/$ss/${array[$f]}}

fi

let f++

done

f=0

let k++

let i++

done

echo "$str"

Output: [su@localhost pgm]$ bash upperlower

Enter the string

ComPutErSciENcE

The string length is:15

COMpUTeRsCIence

[su@localhost pgm]$

Result: Thus the above program to covert the upper case into lower case

and vice versa were executed successfully.

Operating System 57

3. Find the number of vowels in a given string

Aim:

To find the vowels in a string

Procedure:

7) Create a new vi editor file.


9) Find the length and substring of the given string.

10) Initialize the count value (i.e.) count=0.

11) If the substring character is match with any vowels character then

increase the count value.

12) Print the count value

Program: #!bin/bash

echo "Enter the string"

read str

k=${#str}

echo "The string Length is:$k"

i=0

d=1

j=0

count=0

while [ $j -lt $k ]

do

g=${str:$i:$d}

if [ $g = a -o $g = e -o $g = i -o $g = o -o $g = u -o $g = A -o $g = E -o

$g =I -o $g = O -o $g = U ]

then

let count++

fi

let i++

let j++

done

echo "Number of vowels in the given string is:$count"

Operating System 58

Output: [su@localhost su]$ bash vowels

Enter the string

Kanyakumari

The string Length is:11

Number of vowels in the given string is:5

Result: Thus the above program to find the number of vowels present in a given

string was executed successfully.

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