OS-Linux-commands-Shell-scripting

Operating systems Lab exercise

Linux commands-Shell scripting

Linux commands-Shell scripting

AIM:

To practice Linux Commands and Shell Scripting

DESIGN STEPS:

Step 1:

Navigate to any Linux environment installed on the system or installed inside a virtual environment like virtual box/vmware or online linux JSLinux (https://bellard.org/jslinux/vm.html?url=alpine-x86.cfg&mem=192) or docker.

Step 2:

Execute the following commands

Step 3:

Testing the commands for the desired output.

COMMANDS:

Create the following files file1, file2 as follows:

cat > file1

chanchal singhvi
c.k. shukla
s.n. dasgupta
sumit chakrobarty
^d

cat > file2

anil aggarwal
barun sengupta
c.k. shukla
lalit chowdury
s.n. dasgupta
^d

Display the content of the files

cat < file1

OUTPUT

chanchal singhvi c.k. shukla s.n. dasgupta sumit chakrobarty

cat < file2

OUTPUT

anil aggarwal barun sengupta c.k. shukla lalit chowdury s.n. dasgupta

Comparing Files

cmp file1 file2

OUTPUT

file1 file2 differ: char1,line1 comm file1 file2

OUTPUT

anil aggarwal barun sengupta c.k. shukla chanchal singhvi c.k. shukla lalit chowdury s.n. dasgupta

diff file1 file2

OUTPUT

--- file1 +++ file2 @@ -1,4 +1,5 @@ -chanchal singhvi +anil aggarwal +barun sengupta c.k. shukla +lalit chowdury s.n. dasgupta -sumit chakrobarty

#Filters

Create the following files file11, file22 as follows:

cat > file11

Hello world
This is my world
^d

cat > file22

1001 | Ram | 10000 | HR
1002 | tom |  5000 | Admin
1003 | Joe |  7000 | Developer
^d

cut -c1-3 file11

OUTPUT

Hel Thi

cut -d "|" -f 1 file22

OUTPUT

1001 1002 1003

cut -d "|" -f 2 file22

OUTPUT

Ram tom Joe

cat < newfile

Hello world
hello world
^d

cat > newfile Hello world hello world

grep Hello newfile

OUTPUT

Hello world

grep hello newfile

OUTPUT

hello world

grep -v hello newfile

OUTPUT

Hello world

cat newfile | grep -i "hello"

OUTPUT

Hello world hello world

cat newfile | grep -i -c "hello"

OUTPUT

2

grep -R ubuntu /etc

OUTPUT

recursion

grep -w -n world newfile

OUTPUT

1:Hello world 2:hello world

cat < newfile

Hello world
hello world
Linux is world number 1
Unix is predecessor
Linux is best in this World
^d

cat > newfile

Hello world
hello world
Linux is world number 1
Unix is predecessor
Linux is best in this World
^d

egrep -w 'Hello|hello' newfile

OUTPUT

Hello world hello world

egrep -w '(H|h)ello' newfile

OUTPUT

Hello world hello world

egrep -w '(H|h)ell[a-z]' newfile

OUTPUT

Hello world hello world

egrep '(^hello)' newfile

OUTPUT

hello world

egrep '(world$)' newfile

OUTPUT

Hello world hello world

egrep '(World$)' newfile

OUTPUT

Linux is best in the World

egrep '((W|w)orld$)' newfile

OUTPUT

Hello world hello world Linux is best in this World

egrep '[1-9]' newfile

OUTPUT

Linux is world number 1

egrep 'Linux.*world' newfile

OUTPUT

Linux is world number 1

egrep 'Linux.*World' newfile

OUTPUT

Linux is best in this World

egrep l{2} newfile

OUTPUT

Hello world hello world

egrep 's{1,2}' newfile

OUTPUT

Unix is predecessor Linux is best in this World

cat > file23

1001 | Ram | 10000 | HR
1001 | Ram | 10000 | HR
1002 | tom |  5000 | Admin
1003 | Joe |  7000 | Developer
1005 | Sam |  5000 | HR
1004 | Sit |  7000 | Dev
1003 | Joe |  7000 | Developer
1001 | Ram | 10000 | HR
^d

sed -n -e '3p' file23

OUTPUT

1002 | tom | 5000 | Admin

sed -n -e '$p' file23

OUTPUT

1001 | Ram | 10000 | HR

sed -e 's/Ram/Sita/' file23

OUTPUT

1001 | Sita | 10000 | HR 1001 | Sita | 10000 | HR 1002 | tom | 5000 | Admin 1003 | Joe | 7000 | Developer 1005 | Sam | 5000 | HR 1004 | Sit | 7000 | Dev 1003 | Joe | 7000 | Developer 1001 | Sita | 10000 | HR

sed -e '2s/Ram/Sita/' file23

OUTPUT

1001 | Ram | 10000 | HR 1001 | Sita | 10000 | HR 1002 | tom | 5000 | Admin 1003 | Joe | 7000 | Developer 1005 | Sam | 5000 | HR 1004 | Sit | 7000 | Dev 1003 | Joe | 7000 | Developer 1001 | Ram | 10000 | HR

sed '/tom/s/5000/6000/' file23

OUTPUT

1001 | Ram | 10000 | HR 1001 | Ram | 10000 | HR 1002 | tom | 6000 | Admin 1003 | Joe | 7000 | Developer 1005 | Sam | 5000 | HR 1004 | Sit | 7000 | Dev 1003 | Joe | 7000 | Developer 1001 | Ram | 10000 | HR

sed -n -e '1,5p' file23

OUTPUT

1001 | Ram | 10000 | HR 1001 | Ram | 10000 | HR 1002 | tom | 5000 | Admin 1003 | Joe | 7000 | Developer 1005 | Sam | 5000 | HR

sed -n -e '2,/Joe/p' file23

OUTPUT

1001 | Ram | 10000 | HR 1002 | tom | 5000 | Admin 1003 | Joe | 7000 | Developer

sed -n -e '/tom/,/Joe/p' file23

OUTPUT

1002 | tom | 5000 | Admin 1003 | Joe | 7000 | Developer

seq 10

OUTPUT

1 2 3 4 5 6 7 8 9 10

seq 10 | sed -n '4,6p'

OUTPUT

4 5 6

seq 10 | sed -n '2,~4p'

OUTPUT

2 3 4

seq 3 | sed '2a hello'

OUTPUT

1 2 hello 3

seq 2 | sed '2i hello'

OUTPUT

1 hello 2

seq 10 | sed '2,9c hello'

OUTPUT

1 hello 10

sed -n '2,4{s/^/$/;p}' file23

OUTPUT

$1001 | Ram | 10000 | HR $1002 | tom | 5000 | Admin $1003 | Joe | 7000 | Developer

sed -n '2,4{s/$/*/;p}' file23

OUTPUT

1001 | Ram | 10000 | HR* 1002 | tom | 5000 | Admin* 1003 | Joe | 7000 | Developer*

#Sorting File content cat > file21

1001 | Ram | 10000 | HR
1002 | tom |  5000 | Admin
1003 | Joe |  7000 | Developer
1005 | Sam |  5000 | HR
1004 | Sit |  7000 | Dev

sort file21

OUTPUT

1001 | Ram | 10000 | HR 1002 | tom | 5000 | Admin 1003 | Joe | 7000 | Developer 1004 | Sit | 7000 | Dev 1005 | Sam | 5000 | HR

cat > file22

1001 | Ram | 10000 | HR
1001 | Ram | 10000 | HR
1002 | tom |  5000 | Admin
1003 | Joe |  7000 | Developer
1005 | Sam |  5000 | HR
1004 | Sit |  7000 | Dev

uniq file22

OUTPUT

1001 | Ram | 10000 | HR 1002 | tom | 5000 | Admin 1003 | Joe | 7000 | Developer 1005 | Sam | 5000 | HR 1004 | Sit | 7000 | Dev

#Using tr command

cat file23 | tr [:lower:] [:upper:]

OUTPUT

1001 | RAM | 10000 | HR 1001 | RAM | 10000 | HR 1002 | TOM | 5000 | ADMIN 1003 | JOE | 7000 | DEVELOPER 1005 | SAM | 5000 | HR 1004 | SIT | 7000 | DEV 1003 | JOE | 7000 | DEVELOPER 1001 | RAM | 10000 | HR cat < urllist.txt

www. yahoo. com
www. google. com
www. mrcet.... com
^d

cat > urllist.txt

www. yahoo. com
www. google. com
www. mrcet.... com

cat urllist.txt | tr -d ' '

OUTPUT

www.yahoo.com www.google.com www.mrcet....com

cat urllist.txt | tr -d ' ' | tr -s '.'

OUTPUT

www.yahoo.com www.google.com www.mrcet.com

#Backup commands tar -cvf backup.tar *

OUTPUT

bench.py file1 file11 file2 file21 file22 file23 hello.c hello.js newfile readme.txt urllist.txt

mkdir backupdir

mv backup.tar backupdir

tar -tvf backup.tar

OUTPUT

-rw-r--r-- user/group 0 2024-02-25 14:30:00 file1.txt drwxr-xr-x user/group 0 2024-02-25 14:30:00 directory1/ -rw-r--r-- user/group 1024 2024-02-25 14:30:00 directory1/file2.txt -rw-r--r-- user/group 2048 2024-02-25 14:30:00 directory1/file3.txt

tar -xvf backup.tar

OUTPUT

x file1.txt x directory1/ x directory1/file2.txt x directory1/file3.txt gzip backup.tar

ls .gz

OUTPUT

backup.tar.gz gunzip backup.tar.gz

OUTPUT

backup.tar

Shell Script

echo '#!/bin/sh' > my-script.sh
echo 'echo Hello World‘; exit 0 >> my-script.sh

chmod 755 my-script.sh ./my-script.sh

OUTPUT

echo Hello World

cat << stop > herecheck.txt

hello in this world
i cant stop
for this non stop movement
stop

cat herecheck.txt

OUTPUT

hello in this world i cant stop for this non stop movement

cat < scriptest.sh

\#!/bin/sh
echo “File name is $0 ”
echo "File name is " `basename $0`
echo “First arg. is ” $1
echo “Second arg. is ” $2
echo “Third arg. is ” $3
echo “Fourth arg. is ” $4
echo 'The $@ is ' $@
echo 'The $\# is ' $1#
echo 'The $$ is ' $$
ps
^d

cat scriptest.sh

\#!/bin/sh
echo “File name is $0 ”
echo "File name is " `basename $0`
echo “First arg. is ” $1
echo “Second arg. is ” $2
echo “Third arg. is ” $3
echo “Fourth arg. is ” $4
echo 'The $@ is ' $@
echo 'The $\# is ' $\#
echo 'The $$ is ' $$
ps

chmod 777 scriptest.sh

./scriptest.sh 1 2 3

OUTPUT

File name is ./scriptest.sh File name is scriptest.sh First arg. is 1 Second arg. is 2 Third arg. is 3 Fourth arg. is The $@ is 1 2 3 The $# is $# The $$ is 124

ls file1

OUTPUT

file1 echo $?

OUTPUT

0

echo $?

OUTPUT

abcd

echo $?

OUTPUT

1

mis-using string comparisons

cat < strcomp.sh

\#!/bin/bash
val1=baseball
val2=hockey
if [ $val1 \> $val2 ]
then
echo "$val1 is greater than $val2"
else
echo "$val1 is less than $val2"
fi
^d

cat strcomp.sh

\#!/bin/bash
val1=baseball
val2=hockey
if [ $val1 \> $val2 ]
then
echo "$val1 is greater than $val2"
else
echo "$val1 is less than $val2"
fi

##OUTPUT val1=baseball val2=hockey if [ $val1 > $val2 ] then echo "$val1 is greater than $val2" else echo "$val1 is less than $val2" fi

chmod 755 strcomp.sh

./strcomp.sh

OUTPUT

baseball is less than hockey

check file ownership

cat < psswdperm.sh

\#!/bin/bash
if [ -O /etc/passwd ]
then
echo “You are the owner of the /etc/passwd file”
else
echo “Sorry, you are not the owner of the /etc/passwd file”
fi
^d

cat psswdperm.sh

/#!/bin/bash
if [ -O /etc/passwd ]
then
echo “You are the owner of the /etc/passwd file”
else
echo “Sorry, you are not the owner of the /etc/passwd file”
fi

./psswdperm.sh

OUTPUT

You are the owner of the /etc/passwd file

check if with file location

cat>ifnested.sh

\#!/bin/bash
if [ -e $HOME ]
then
echo “$HOME The object exists, is it a file?”
if [ -f $HOME ]
then
echo “Yes,$HOME it is a file!”
else
echo “No,$HOME it is not a file!”
if [ -f $HOME/.bash_history ]
then
echo “But $HOME/.bash_history is a file!”
fi
fi
else
echo “Sorry, the object does not exist”
fi
^d

cat ifnested.sh

\#!/bin/bash
if [ -e $HOME ]
then
echo “$HOME The object exists, is it a file?”
if [ -f $HOME ]
then
echo “Yes,$HOME it is a file!”
else
echo “No,$HOME it is not a file!”
if [ -f $HOME/.bash_history ]
then
echo “But $HOME/.bash_history is a file!”
fi
fi
else
echo “Sorry, the object does not exist”
fi

./ifnested.sh

OUTPUT

/root The object exists, is it a file? No,/root it is not a file!

using numeric test comparisons

cat > iftest.sh

\#!/bin/bash
val1=10
val2=11
if [ $val1 -gt 5 ]
then
echo “The test value $val1 is greater than 5”
fi
if [ $val1 -eq $val2 ]
then
echo “The values are equal”
else
echo “The values are different”
fi
^d

cat iftest.sh

\#!/bin/bash
val1=10
val2=11
if [ $val1 -gt 5 ]
then
echo “The test value $val1 is greater than 5”
fi
if [ $val1 -eq $val2 ]
then
echo “The values are equal”
else
echo “The values are different”
fi

$ chmod 755 iftest.sh

$ ./iftest.sh ##OUTPUT “The test value 10 is greater than 5” “The values are different”

check if a file

cat > ifnested.sh

\#!/bin/bash
if [ -e $HOME ]
then
echo “$HOME The object exists, is it a file?”
if [ -f $HOME ]
then
echo “Yes,$HOME it is a file!”
else
echo “No,$HOME it is not a file!”
if [ -f $HOME/.bash_history ]
then
echo “But $HOME/.bash_history is a file!”
fi
fi
else
echo “Sorry, the object does not exist”
fi
^d

cat ifnested.sh

\#!/bin/bash
if [ -e $HOME ]
then
echo “$HOME The object exists, is it a file?”
if [ -f $HOME ]
then
echo “Yes,$HOME it is a file!”
else
echo “No,$HOME it is not a file!”
if [ -f $HOME/.bash_history ]
then
echo “But $HOME/.bash_history is a file!”
fi
fi
else
echo “Sorry, the object does not exist”
fi

$ chmod 755 ifnested.sh

$ ./ifnested.sh ##OUTPUT “/root The object exists, is it a file?” “No,/root it is not a file!”

looking for a possible value using elif

cat elifcheck.sh

\#!/bin/bash
if [ $USER = Ram ]
then
echo "Welcome $USER"
echo "Please enjoy your visit"
elif [ $USER = Rahim ]
then
echo "Welcome $USER"
echo "Please enjoy your visit"
elif [ $USER = Robert ]
then
echo "Special testing account"
elif [ $USER = gganesh ]
then
echo "$USER, Do not forget to logout when you're done"
else
echo "Sorry, you are not allowed here"
fi

$ chmod 755 elifcheck.sh

$ ./elifcheck.sh

OUTPUT

Welcome Ram Please enjoy your visit Welcome Rahim Please enjoy your visit Special testing account gganesh, Do not forget to logout when you're done Sorry, you are not allowed here

testing compound comparisons

cat> ifcompound.sh

\#!/bin/bash
if [ -d $HOME ] && [ -w $HOME ]
then
echo "The file exists and you can write to it"
else
echo "I cannot write to the file"
fi

$ chmod 755 ifcompound.sh $ ./ifcompound.sh

OUTPUT

The file exists and you can write to it

using the case command

cat >casecheck.sh

case $USER in
Ram | Robert)
echo "Welcome, $USER"
echo "Please enjoy your visit";;
Rahim)
echo "Special testing account";;
gganesh)
echo "$USER, Do not forget to log off when you're done";;
*)
echo "Sorry, you are not allowed here";;
esac

$ chmod 755 casecheck.sh

$ ./casecheck.sh

OUTPUT

Welcome Ram/Rahim Please enjoy your visit Special testing account gganesh, Do not forget to logout when you're done Sorry, you are not allowed here cat > whiletest

#!/bin/bash
#while command test
var1=10
while [ $var1 -gt 0 ]
do
echo $var1
var1=$[ $var1 - 1 ]
done

$ chmod 755 whiletest.sh

$ ./whiletest.sh

OUTPUT

10 9 8 7 6 5 4 3 2 1

cat untiltest.sh

\#using the until command
var1=100
until [ $var1 -eq 0 ]
do
echo $var1
var1=$[ $var1 - 25 ]
done

$ chmod 755 untiltest.sh $ ./ untiltest.sh

OUTPUT

100 75 50 25

cat forin1.sh

\#!/bin/bash
\#basic for command
for test in Alabama Alaska Arizona Arkansas California Colorado
do
echo The next state is $test
done

$ chmod 755 forin1.sh $ ./forin1.sh

OUTPUT

The next state is Alabama The next state is Alaska The next state is Arizona The next state is Arkansas The next state is California The next state is Colorado

cat forin2.sh

\#!/bin/bash
\# another example of how not to use the for command
for test in I don't know if this'll work
do
echo “word:$test”
done

$ chmod 755 forin2.sh

$ ./forin2.sh

OUTPUT

word:I word:dont know if thisll word:work cat forin3.sh

\#!/bin/bash
\# another example of how not to use the for command
for test in I don\'t know if "this'll" work
do
echo "word:$test"
done

$ ./forin3.sh

OUTPUT

word:I word:don't word:know word:if word:this'll word:work

cat forinfile.sh

#!/bin/bash
# reading values from a file
file="cities"
for state in `cat $file`
do
echo "Visit beautiful $file“
done

$ chmod 777 forinfile.sh $ cat cities Hyderabad Alampur Basara Warangal Adilabad Bhadrachalam Khammam

OUTPUT

Visit beautiful Hyderabad Visit beautiful Alampur Visit beautiful Basara Visit beautiful Warangal Visit beautiful Adilabad Visit beautiful Bhadrachalam Visit beautiful Khammam

cat forctype.sh

#!/bin/bash
# testing the C-style for loop
for (( i=1; i <= 5; i++ ))
do
echo "The value of i is $i"
done

$ chmod 755 forctype.sh $ ./forctype.sh

OUTPUT

The value of i is 1 The value of i is 2 The value of i is 3 The value of i is 4 The value of i is 5

cat forctype1.sh

#!/bin/bash
# multiple variables
for (( a=1, b=5; a <= 5; a++, b-- ))
do
echo "$a - $b"
done

$ chmod 755 forctype.sh $ ./forctype1.sh

OUTPUT

cat fornested1.sh

#!/bin/bash
# nesting for loops
for (( a = 1; a <= 3; a++ ))
do
echo "Starting loop $a:"
for (( b = 1; b <= 3; b++ ))
do
echo " Inside loop: $b"
done
done

$ chmod 755 fornested1.sh

$ ./fornested1.sh

OUTPUT

1 - 5 2 - 4 3 - 3 4 - 2 5 - 1

cat forbreak.sh

#!/bin/bash
# breaking out of a for loop
for var1 in 1 2 3 4 5
do
if [ $var1 -eq 3 ]
then
break
fi
echo "Iteration number: $var1"
done
echo "The for loop is completed“

$ chmod 755 forbreak.sh

$ ./forbreak.sh

OUTPUT

Iteration number: 1 Iteration number: 2 The for loop is completed

cat forcontinue.sh

#!/bin/bash
# breaking out of a for loop
for var1 in 1 2 3 4 5
do
if [ $var1 -eq 3 ]
then
continue
fi
echo "Iteration number: $var1"
done
echo "The for loop is completed“

$ chmod 755 forcontinue.sh

$ ./forcontinue.sh

OUTPUT

Iteration number: 1 Iteration number: 2 Iteration number: 4 Iteration number: 5 The for loop is completed

cat exread.sh

#!/bin/bash
# testing the read command
echo -n "Enter your name: "
read name
echo "Hello $name, welcome to my program. "

$ chmod 755 exread.sh

$ ./exread.sh

OUTPUT

Enter your name: John Hello John, welcome to my program.

cat exread1.sh

#!/bin/bash
# testing the read command
read -p "Enter your name: " name
echo "Hello $name, welcome to my program. “

$ chmod 755 exread1.sh

OUTPUT

Enter your name: sanju Hello sanju, welcome to my program.

$ ./exread1.sh

cat funcex.sh

#!/bin/bash
# trying to access script parameters inside a function
function func {
echo $[ $1 * $2 ]
}
if [ $# -eq 2 ]
then
value=`func $1 $2`
echo "The result is $value"
else
echo "Usage: badtest1 a b"
fi

OUTPUT

./funcex.sh

./funcex.sh 1 2 $ bash script.sh 1 2 The result is 2

cat argshift.sh

#!/bin/bash 
 while (( "$#" )); do 
  echo $1 
  shift 
done

$ chmod 777 argshift.sh

OUTPUT

$ ./argshift.sh 1 2 3 1 2 3 cat argshift1.sh

 #/bin/bash 
 # store arguments in a special array 
args=("$@") 
# get number of elements 
ELEMENTS=${#args[@]} 
 # echo each element in array  
# for loop 
for (( i=0;i<$ELEMENTS;i++)); do 
    echo ${args[${i}]} 
done

$ chmod 777 argshift.sh

OUTPUT

$ ./argshift.sh 1 2 3 1 2 3 cat argshift.sh

#!/bin/bash 
set -x 
while (( "$#" )); do 
  echo $1 
  shift 
done
set +x

OUTPUT

./argshift.sh 1 2 3

• (( 0 ))
• set +x

cat > nc.awk

BEGIN{}
{
print len=length($0),"\t",$0 
wordcount+=NF
chrcnt+=len
}
END {
print "total characters",chrcnt 
print "Number of Lines are",NR
print "No of Words count:",wordcount
}

cat>data.dat

bcdfghj
abcdfghj
bcdfghj
ebcdfghj
bcdfghj
ibcdfghj
bcdfghj
obcdfghj
bcdfghj
ubcdfghj

awk -f nc.awk data.dat

OUTPUT

total characters 75 Number of Lines are 10 No of Words count: 10 cat > palindrome.sh

#num=545
echo "Enter the number"
read num
s=0
rev=""
temp=$num
while [ $num -gt 0 ]
do
	# Get Remainder
	s=$(( $num % 10 ))
	# Get next digit
	num=$(( $num / 10 ))
	# Store previous number and
	# current digit in reverse
	rev=$( echo ${rev}${s} )
done
if [ $temp -eq $rev ];
then
	echo "Number is palindrome"
else
	echo "Number is NOT palindrome"
fi

OUTPUT

Enter the number 121 Number is palindrome Enter the number 69 Number is NOT palindrome

RESULT:

The Commands are executed successfully.