Mathematical Aspect of Linux Shell Programming – Part IV

In this post I will be discussing the Scripts from the Mathematical and Number point of view. Although I have posted a more complex script (Simple Calculator) in the previous post, but on a user part it was difficult to understand and hence I thought to make you people learn the other useful side of learning in small packets.

Let’s start the further learning process with some new exciting scripts, start with Mathematics scripts:

Script 1: Additions

Create a file “Addition.sh” and chmod 755 to the script as described in previous post and run it.

#!/bin/bash

echo “Enter the First Number: ” 

read a 

echo “Enter the Second Number: ” 

read b 

x=$(expr "$a" + "$b") 

echo $a + $b = $x

Sample Output

[root@localhost ~]# vi Additions.sh

[root@localhost ~]# chmod 755 Additions.sh

[root@localhost ~]# ./Additions.sh

“Enter the First Number: ” 

12 

“Enter the Second Number: ” 

13 

12 + 13 = 25

Script 2: Substraction

#!/bin/bash

echo “Enter the First Number: ” 

read a 

echo “Enter the Second Number: ” 

read b 

x=$(($a - $b)) 

echo $a - $b = $x

Note: Here we replaced the expr and let the mathematical calculation be performed in shell.

Sample Output

[root@localhost ~]# vi Substraction.sh

[root@localhost ~]# chmod 755 Substraction.sh

[root@localhost ~]# ./Substraction.sh

“Enter the First Number: ” 

13 

“Enter the Second Number: ” 

20 

13 - 20 = -7

Script 3: Multiplication

So far you would be enjoying a lot, learning scripts in such an easy way, so the next in chronological order is Multiplication.

#!/bin/bash

echo “Enter the First Number: ” 

read a 

echo “Enter the Second Number: ” 

read b 

echo "$a * $b = $(expr $a \* $b)"

Note: Yup! Here we didn’t put the value of multiplication in a variable but performed it directly in output statement.

Sample Output

[root@localhost ~]# vi Multiplication.sh

[root@localhost ~]# chmod 755 Multiplication.sh

[root@localhost ~]# ./Multiplication.sh

“Enter the First Number: ” 

11 

“Enter the Second Number: ” 

11 

11 * 11 = 121

Script 4: Division

Right! Next is Division, and again it is a very simple script. Check it Yourself.

#!/bin/bash

echo “Enter the First Number: ” 

read a 

echo “Enter the Second Number: ” 

read b 

echo "$a / $b = $(expr $a / $b)"

Sample Output

[root@localhost ~]# vi Division.sh

[root@localhost ~]# chmod 755 Division.sh

[root@localhost ~]# ./Division.sh

“Enter the First Number: ” 

12 

“Enter the Second Number: ” 

3 

12 / 3 = 4

Script 5: Table

Fine! What after these basic mathematical operation. Lets write a script that prints table of any number.

#!/bin/bash

echo “Enter The Number upto which you want to Print Table: ” 

read n 

i=1 

while [ $i -ne 10 ] 

do 

i=$(expr $i + 1) 

table=$(expr $i \* $n) 

echo $table 

done

Sample Output

[root@localhost ~]# vi Table.sh

[root@localhost ~]# chmod 755 Table.sh

[root@localhost ~]# ./Table.sh

“Enter The Number upto which you want to Print Table: ” 

29 

58 

87 

116 

145 

174 

203 

232 

261 

290

Script 6: EvenOdd

We as a child always have carried out calculation to find if the number is odd or even. Won’t it be a good idea to implement it in script.

#!/bin/bash

echo "Enter The Number" 

read n 

num=$(expr $n % 2) 

if [ $num -eq 0 ] 

then 

echo "is a Even Number" 

else 

echo "is a Odd Number" 

fi

Sample Output

[root@localhost ~]# vi EvenOdd.sh

[root@localhost ~]# chmod 755 EvenOdd.sh

[root@localhost ~]# ./EvenOdd.sh

Enter The Number 

12 

is a Even Number

[root@localhost ~]# ./EvenOdd.sh

Enter The Number 

11 

is a Odd Number

Script 7: Factorial

Next is to find the Factorial.

#!/bin/bash 

echo "Enter The Number" 

read a 

fact=1 

while [ $a -ne 0 ] 

do 

fact=$(expr $fact \* $a) 

a=$(expr $a - 1) 

done 

echo $fact

Sample Output

[root@localhost ~]# vi Factorial.sh

[root@localhost ~]# chmod 755 Factorial.sh

[root@localhost ~]# ./Factorial.sh

Enter The Number 

12 

479001600

You may now relax with a feeling that calculating 12*11*10*9*7*7*6*5*4*3*2*1 would be more difficult than a simple script as produced above. Think of the situation where you require to find 99! or something like that. Sure! This script will be very much handy in that situation.

Script 8: Armstrong

Armstrong Number! Ohhh You forget what an Armstrong Number is. Well an Armstrong number of three digits is an integer such that the sum of the cubes of its digits is equal to the number itself. For example, 371 is an Armstrong number since 3**3 + 7**3 + 1**3 = 371.

#!/bin/bash 

echo "Enter A Number" 

read n 

arm=0 

temp=$n 

while [ $n -ne 0 ] 

do 

r=$(expr $n % 10) 

arm=$(expr $arm + $r \* $r \* $r) 

n=$(expr $n / 10) 

done 

echo $arm 

if [ $arm -eq $temp ] 

then 

echo "Armstrong" 

else 

echo "Not Armstrong" 

fi

Sample Output

[root@localhost ~]# vi Armstrong.sh

[root@localhost ~]# chmod 755 Armstrong.sh

[root@localhost ~]# ./Armstrong.sh

Enter A Number 

371 

371 

Armstrong

[root@localhost ~]# ./Armstrong.sh

Enter A Number 

123 

36 

Not Armstrong

Script 9: Prime

The last script is to distinguish whether a number is prime or not.

#!/bin/bash 

echo “Enter Any Number”

read n

i=1

c=1

while [ $i -le $n ]

do

i=$(expr $i + 1)

r=$(expr $n % $i)

if [ $r -eq 0 ]

then

c=$(expr $c + 1)

fi

done

if [ $c -eq 2 ]

then

echo “Prime”

else

echo “Not Prime”

fi

Sample Output

[root@localhost ~]# vi Prime.sh

[root@localhost ~]# chmod 755 Prime.sh

[root@localhost ~]# ./Prime.sh

“Enter Any Number” 

12 

“Not Prime”

That’s all for now. In our very next article we will be covering other mathematical programs in the shell Scripting programming language. Don’t forget to mention your views regarding article in the Comment section. Like and share us and help us spread.