OS Lab Manual

GECG Gandhinagar CE

Government Engineering College Sector-28, Gandhinagar Computer Department

BE II SEM IV Operating System

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UNIX Commands 1) pwd COMMAND:

Pwd - Print Working Directory. pwd command prints the full filename of the current

working directory.

SYNTAX:

The Syntax is

pwd [options]

2) cd COMMAND:

cd command is used to change the directory.

SYNTAX:

The Syntax is

cd [directory | ~ | ./ | ../ | - ]

3) ls COMMAND:

ls command lists the files and directories under current working directory.

SYNTAX:

The Syntax is

ls [OPTIONS]... [FILE]

OPTIONS:

-l Lists all the files, directories and their mode, Number of links,

owner of the file, file size, Modified date and time and filename.

-t Lists in order of last modification time.

-a Lists all entries including hidden files.

-d Lists directory files instead of contents.

-p Puts slash at the end of each directories.

-u List in order of last access time.

-i Display inode information.

4) rm COMMAND:

rm linux command is used to remove/delete the file from the directory.

SYNTAX:

The Syntax is

rm [options..] [file | directory]

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OPTIONS:

-f Remove all files in a directory without prompting the user.

-I Interactive. With this option, rm prompts for confirmation before

removing any files.

5) mv COMMAND:

mv command which is short for move. It is used to move/rename file

from one directory to another. mv command is different from cp command

as it completely removes the file from the source and moves to the directory specified, where cp

command just copies the content from one file to another.

SYNTAX:

The Syntax is

mv [-f] [-i] oldname newname

OPTIONS:

-f This will not prompt before overwriting (equivalent to --reply=yes). mv -f will move the file(s)

without prompting even if it is writing over an existing target.

-i Prompts before overwriting another file.

6) cat COMMAND:

cat linux command concatenates files and print it on the standard output.

SYNTAX:

The Syntax is

cat [OPTIONS] [FILE]...

OPTIONS:

-A Show all.

-b Omits line numbers for blank space in the output.

-E Displays a $ (dollar sign) at the end of each line.

-n Line numbers for all the output lines.

7) cmp COMMAND:

cmp linux command compares two files and tells you which line numbers are different.

SYNTAX:

The Syntax is

cmp [options..] file1 file2

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OPTIONS:

- c Output differing bytes as characters.

- l Print the byte number (decimal) and the differing byte values

(octal) for each difference.

- s Prints nothing for differing files, return exit status only.

8) cp COMMAND:

cp command copy files from one location to another. If the

destination is an existing file, then the file is overwritten; if the destination is

an existing directory, the file is copied into the directory (the directory is not

overwritten).

SYNTAX:

The Syntax is

cp [OPTIONS]... SOURCE DEST

10) echo COMMAND:

echo command prints the given input string to standard output.

SYNTAX:

The Syntax is

echo [options..] [string]

11) mkdir COMMAND:

mkdir command is used to create one or more directories.

SYNTAX:

The Syntax is

mkdir [options] directories

OPTIONS:

-m Set the access mode for the new directories.

-p Create intervening parent directories if they don't exist.

-v Print help message for each directory created.

12) paste COMMAND:

paste command is used to paste the content from one file to another file. It is also used to

set column format for each line.

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SYNTAX:

The Syntax is

paste [options]

OPTIONS:

-s Paste one file at a time instead of in parallel.

-d Reuse characters from LIST instead of TABs .

13) rmdir COMMAND:

rmdir command is used to delete/remove a directory and its subdirectories.

SYNTAX:

The Syntax is

rmdir [options..] Directory

OPTIONS:

-p

Allow users to remove the directory dir name and its parent directories which become empty.

Modify a user account. Changes may be made to the password, group

membership, expiration date, and other attributes of a given user's account.

With this command, a user's password may be locked, which has the effect

of disabling the account.

25

groupmod

Modify a given group. The group name and/or ID number may be changed

using this command.

14) cal

This command will print a calendar for a specified month and/or year.

To show this month's calendar, enter:

cal

To show a twelve-month calendar for 2008, enter:

cal 2008

To show a calendar for just the month of June 1970, enter:

cal 6 1970

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15) cat

This command outputs the contents of a text file. You can use it to read brief files or to

concatenate files together.

To append file1 onto the end of file2, enter:

cat file1 >> file2

To view the contents of a file named myfile, enter:

cat myfile

16) cd

This command changes your current directory location. By default, your Unix login session

begins in your home directory.

To switch to a subdirectory (of the current directory) named myfiles, enter:

cd myfiles

To switch to a directory named /home/dvader/empire_docs, enter:

cd /home/dvader/empire_docs

To move to the parent directory of the current directory, enter:

cd ..

To move to the root directory, enter:

cd /

To return to your home directory, enter:

cd

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17) chmod

This command changes the permission information associated with a file. Every file (including

directories, which Unix treats as files) on a Unix system is stored with records indicating who

has permission to read, write, or execute the file, abbreviated as r, w, and x. These permissions

are broken down for three categories of user: first, the owner of the file; second, a group with

which both the user and the file may be associated; and third, all other users. These categories

are abbreviated as u for owner (or user), g for group, and o for other.

To allow yourself to execute a file that you own named myfile, enter:

chmod u+x myfile

To allow anyone who has access to the directory in which myfile is stored to read or execute

myfile, enter:

chmod o+rx myfile

18) cp

This command copies a file, preserving the original and creating an identical copy. If you already

have a file with the new name, cp will overwrite and destroy the duplicate. For this reason, it's

safest to always add -i after the cp command, to force the system to ask for your approval

before it destroys any files. The general syntax for cp is:

cp -i oldfile newfile

To copy a file named meeting1 in the directory /home/dvader/notes to your current directory,

enter:

cp -i /home/dvader/notes/meeting1 .

The . (period) indicates the current directory as destination, and the -i ensures that if there is

another file named meeting1 in the current directory, you will not overwrite it by accident.

To copy a file named oldfile in the current directory to the new name newfile in the mystuff

subdirectory of your home directory, enter:

cp -i oldfile ~/mystuff/newfile

The ~ character (tilde) is interpreted as the path of your home directory.

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Note: You must have permission to read a file in order to copy it.

19) date

The date command displays the current day, date, time, and year.

To see this information, enter:

date

20) df

This command reports file system disk usage (i.e., the amount of space taken up on mounted file

systems). For each mounted file system, df reports the file system device, the number of blocks

used, the number of blocks available, and the directory where the file system is mounted.

To find out how much disk space is used on each file system, enter the following command:

df

If the df command is not configured to show blocks in kilobytes by default, you can issue the

following command:

df -k

21) du

This command reports disk usage (i.e., the amount of space taken up by a group of files). The du

command descends all subdirectories from the directory in which you enter the command,

reporting the size of their contents, and finally reporting a total size for all the files it finds.

To find out how much disk space your files take up, switch to your home directory with the cd

command, and enter:

du

The numbers reported are the sizes of the files; on different systems, these sizes will be in units

of either 512 byte blocks or kilobytes. To learn which is the case, use the man command,

described below. On most systems, du -k will give sizes in kilobytes.

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22) find

The find command lists all of the files within a directory and its subdirectories that match a set

of conditions. This command is most commonly used to find all of the files that have a certain

name.

To find all of the files named myfile.txt in your current directory and all of its subdirectories,

enter:

find . -name myfile.txt -print

To look in your current directory and its subdirectories for all of the files that end in the

extension .txt, enter:

find . -name "*.txt" -print

In these examples, the . (period) represents your current directory. It can be replaced by the full

pathname of another directory to search. For instance, to search for files named myfile.txt in

the directory /home/user/myusername and its subdirectories, enter:

find /home/user/myusername/ -name myfile.txt -print

On some systems, omitting the final / (slash) after the directory name can cause find to fail to

return any results.

As a shortcut for searching in your home directory, enter:

find "$HOME/" -name myfile.txt -print

23) kill

Use this command as a last resort to destroy any jobs or programs that you suspended and are

unable to restart. Use the jobs command to see a list of suspended jobs. To kill suspended job

number three, for example, enter:

kill %3

Now check the jobs command again. If the job has not been cancelled, harsher measures may be

necessary. Enter:

kill -9 %3

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24) ls

This command will list the files stored in a directory. To see a brief, multi-column list of the files

in the current directory, enter:

ls

To also see "dot" files (configuration files that begin with a period, such as .login), enter:

ls -a

To see the file permissions, owners, and sizes of all files, enter:

ls -la

If the listing is long and scrolls off your screen before you can read it, combine ls with the less

utility, for example:

ls -la | less

25) man

This command displays the manual page for a particular command. If you are unsure how to use

a command or want to find out all its options, you might want to try using man to view the

manual page.

For example, to learn more about the ls command, enter:

man ls

26) mv

This command will move a file. You can use mv not only to change the directory location of a

file, but also to rename files. Unlike the cp command, mv will not preserve the original file.

Note: As with the cp command, you should always use -i to make sure you do not overwrite an

existing file.

To rename a file named oldname in the current directory to the new name newname, enter:

mv -i oldname newname

To move a file named hw1 from a subdirectory named newhw to another subdirectory named

oldhw (both subdirectories of the current directory), enter:

mv -i newhw/hw1 oldhw

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If, in this last operation, you also wanted to give the file a new name, such as firsthw, you

would enter:

mv -i newhw/hw1 oldhw/firsthw

27) pwd

This command reports the current directory path. Enter the command by itself:

pwd

GECG Gandhinagar CE

Write a shell script to find factorial of given number n.

echo enter a number;

read n;

i=1;

while [ $n -ne 0 ]

do

i=expr $n\* $i

n=expr $n-1

done

echo factorial of given no. is $i

/*-------------------------INPUT/OUTPUT----------

Enter the n value:

6

The factorial of 6 is:720

-bash-3.2$

---------------------------------------------*/

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Write a shell script which will accept a number and display first n prime numbers as

output.

echo "Enter a number upto which you want the prime numbers: "

read n

echo "Prime numbers upto $n are:"

echo 2

for (( i=2; i

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Write a shell script which will generate first n fibonnacci numbers like: 1, 1, 2, 3, 5, 13,

$ vi fibonacci.sh echo Enter n for Fibonacci series: - read n echo Fibonacci series is: - echo 0 echo 1 i=0 j=1 cnt=2 while [ $cnt le $n ] do k=`expr $i + $j` i= $j j= $k echo $k cnt=`expr $cnt + 1` done Output Enter n for Fibonacci Series:- 10 Fibonacci Series is:- 0 1 1 2 3 5 8

GECG Gandhinagar CE

Display calendar of current month, year

cal command

Just enter cal command as follows:

$ cal

Output:

August 2007

Su Mo Tu We Th Fr Sa

1 2 3 4

5 6 7 8 9 10 11

12 13 14 15 16 17 18

19 20 21 22 23 24 25

26 27 28 29 30 31

ncal command

ncal command changes the output format:

$ ncal

Output:

August 2007

Mo 6 13 20 27

Tu 7 14 21 28

We 1 8 15 22 29

Th 2 9 16 23 30

Fr 3 10 17 24 31

Sa 4 11 18 25

Su 5 12 19 26

Print calendar for year 2008

$ cal 2008

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Display todays date and time

date +%FORMAT

date +"%FORMAT"

var=$(date +"%FORMAT")

Example: Show current time

Open a terminal and type the following command:

date +"%T"

Sample outputs:

16:33:22

To store time to a shell variable called now, enter:

now=$(date +"%T")

echo "Current time : $now"

Sample outputs:

Current time : 13:31:55

Example: 12 hour clock time

Pass the %r format to the date command:

date +"%r"

Sample outputs:

01:37:06 PM

To remove AM or PM from the output use, type:

date +"%I:%M:%S"

Sample outputs:

01:39:30

Sample shell script

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#!/bin/bash

# Purpose: Demo date command and menus

# Author: nixCraft under GPL v2.x+

# ------------------------------------------------------

# Display text at given row and column

show(){

local x=$1

local y=$2

local txt="$3"

# Set cursor position on screen

tput cup $x $y

echo "$txt"

}

while [ : ]

do

clear

# Get the system time

now="$(date +"%r")"

# Show main - menu, server name and time

show 10 10 "MAIN MENU for $HOSTNAME - $now"

show 11 10 "1. System info"

show 12 10 "2. Apache server stats"

show 13 10 "3. MySQL server stats"

show 14 10 "4. Firewall stats"

show 15 10 "5. Exit"

tput cup 16 10; read -t 2 -p "Choice [1-5] ? " usrch

# do something

case $usrch in

1) read -t 2 -p "Showing system info, wait..." fakeinput;;

2) read -t 2 -p "Showing apache info, wait..." fakeinput;;

3) read -t 2 -p "Showing mysqld info, wait..." fakeinput;;

4) read -t 2 -p "Showing firewall info, wait..." fakeinput;;

5) echo "Bye."; exit 0;;

esac

done

Run it as follows:

chmod +x demo.sh

./demo.sh

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Addition of two numbers

echo enter 2 numbers

read a

read b

c=`expr $a + $b`

echo sum of two numbers is $c

OUTPUT:

enter 2 numbers

12

5

multiplication of two numbers is 17

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REVERSE THE NUMBER

echo enter a number

read n

sum=0

while(( n!=0 ))

do

a=èxpr $a % 10`

n=èxpr $n / 10`

sum=èxpr 10 \* sum + $a`

done

echo the reverse of the number is $sum

OUTPUT:

enter the number

1234

the reverse of the number is 4321

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PALINDROME

echo enter a string

read str

count = ècho $str|wc - c`

count = èxpr $count - 1`

while(( $count > 0 ))

do

temp = ècho $str|cut c $count`

temp2=ècho $temp2 & temp`

count èxpr $count - 1`

done

if[ $str == $temp2 ]

then

echo the string is palindrome

else

echo the string is not a palindrome

fi

OUTPUT:

enter the string

malayalam

the string is palindrome

enter the string

kongu

the string is not a palindrome

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STRING COMPARISON

echo enter the two strings

read str 1

read str 2

if [ $str1 == $str2]

then

echo two strings are equal

else

echo two strings are not equal

fi

OUTPUT:

enter the strings:

rose

rose

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ARITHMETIC OPERATIONS

echo enter the 2 numbers

read a

read b

c=èxpr $a + $b`

echo sum of two numbers = $c

d=èxpr $a - $b`

echo subtraction of two numbers= $d

e=èxpr $a \* $b`

echo multiplication of two numbers= $e

f=èxpr $a / $b`

echo division of two numbers= $f

OUTPUT:

enter the two numbers

10

5

sum of two numbers =15

difference of two numbers =5

multiplication of two numbers=50

division of two numbers=2

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MENU DRIVEN CALCULATOR

echo enter the 2 values

read a

read b

echo 1. Addition 2.Subtraction 3.Multiplication 4.Division

echo Enter your choice

read ch

in

1)c=èxpr $a + $b`

echo sum of two numbers = $c

;;

2)c=èxpr $a - $b`

echo subtraction of two numbers= $c

;;

3)c=èxpr $a \* $b`

echo multiplication of two numbers= $c

;;

4)c=èxpr $a / $b`

echo division of two numbers= $c

;;

*)echo Invalid choice

;;

esac

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OUTPUT:

enter the two numbers

10

5

1. Addition 2.Subtraction 3.Multiplication 4.Division

Enter your choice : 3

multiplication of two numbers=50

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GREATEST OF THREE NUMBERS

echo "enter 3 values"

read a

read b

read c

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

then

echo "the greatest value is $a elif [ $b -gt $c ]

then

echo "the greatest value is $b else

echo "the greatest value is $c fi

-

OUTPUT:

enter 3 values

4

8

6

the greatest value is 8

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Employee Details

echo Enter the employee name,designation and basic pay

read name

read design

read basic

case $desig

in

manager) da=èxpr $basic \* 50 /100`

hra=èxpr $basic \* 20 /100`

cca =èxpr $basic \* 10 /100`

pf=3000

loan=1000

;;

Clerk) da=èxpr $basic \* 40 /100`



pf=1500

loan=750

;;

peon) da=èxpr $basic \* 30 /100`



pf=1000

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loan=500

;;

*)echo Invalid designation

;;

esac

gross=`expr $gross - $pf - $loan`

echo Employee Details

echo Employee name : $name

echo Employee designation : $desig

echo Employee basic : Rs $basic

echo Employee da : Rs $da

echo Employee hra : Rs $hra

echo Employee cca : Rs $cca

echo Employee gross : Rs $gross

echo Employee pf : Rs $pf

echo Employee loan : Rs $loan

echo Employee netpay : Rs $netpay

Output:

Enter Employee name,designation and basic pay:

Priya

Manager

20000

Employee Details:

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Name : Priya

Designation : manager

Basic : Rs 20000

Da : Rs 10000

Hra :Rs 2800

cca :Rs 2000

gross pay : Rs 34800

pf : Rs 3000

loan : Rs 1000

netpay : Rs 30800

GECG Gandhinagar CE

Write an interactive file-handling shell program. Let it offer the user the

choice of copying, removing, renaming, or linking files. Once the user has

made a choice, have the program ask the user for the necessary information,

such as the file name and so on.

echo "1.COPY"

echo "2.RENAME"

echo "3.REMOVE"

echo "4.LINK"

echo "5.EXIT"

echo "Enter your choice"

read ch

case $ch in

1) echo "Enter the sources file"

read s

echo "Enter the destination file "

read d

cp $s $d

;;

2) echo "Enter the old file name"

read of

echo "enter the new file name"

read nf

mv $of $nf

;;

3) echo "Enter file name to delete"

read $df

rm $df

;;

4) echo "Enter the file1"

read f1

echo "enter the file2"

read f2

ln $f1 $f2

;;

5) exit 0

;;

Esac

GECG Gandhinagar CE

Write a program to create a process in UNIX.

STEP 1: Start the program.

STEP 2: Declare pid as integer.

STEP 3: Create the process using Fork command.

STEP 4: Check pid is less than 0 then print error else if pid is equal to 0 then execute

command else parent process wait for child process.

STEP 5: Stop the program

PROGRAM:

void main()

{

int id;

id=fork();

if(id

GECG Gandhinagar CE

Display usernames those are currently logged in the system

Using WHO Command

WHO u

Write a shell script that displays a list of all the files in the current directory to which the user has read,

write and execute permissions.

echo "The list of File Names in the curent directory."

echo "Which have Read,Write and Execute permisions. "

for file in *

do

if [ -f $file ]

then

if [ -r $file -a -w $file -a -x $file ]

then

ls -l $file

fi

fi

done

OUTPUT:

$ls -l

total 76

-rw-rw-r-- 1 srianjaneya srianjaneya 159 Sep 5 21:22 10.sh


-rwx--x--x 1 srianjaneya srianjaneya 231 Sep 5 20:04 1.sh

-rw------- 1 srianjaneya srianjaneya 231 Sep 5 20:03 1.sh~

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-rw------- 1 srianjaneya srianjaneya 287 Sep 5 20:16 2.sh~


-rw-rw-r-- 1 srianjaneya srianjaneya 171 Sep 5 20:26 3.sh~


-rw-rw-r-- 1 srianjaneya srianjaneya 249 Sep 5 20:32 4.sh~

The list of File Names in the curent directory.

Which have Read,Write and Execute permisions.



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Write a shell program to concatenate two strings.

Step1: Enter into the vi editor and go to the insert mode for entering the code

Step2: Read the first string.

Step3: Read the second string

Step4: Concatenate the two strings

Step5: Enter into the escape mode for the execution of the result and verify the output

Program:

echo enter the first string read str1

echo enter the second string read str2

echo the concatenated string is $str1$str2

Sample I/P: Enter first string: Hello

Enter first string: World

Sample O/P:

The concatenated string is HelloWorld

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