Write a menu driven program using FUNCTION Linux shell progr

Write a menu driven program using FUNCTION (Linux shell programming language) to test some of the arithmetic operators.

Example:

Main Menu

1--------------------------------ADD

2--------------------------------SUB

3--------------------------------MPY

4--------------------------------MOD

5--------------------------------DIV

6--------------------------------EXIT

The program must prompt user for input i.e.

Please enter two numbers to be added.

Also must print out the input and the result (output).

Answer :

#!/bin/bash
# SCRIPT: ArithematicOperatins.sh
# USAGE: ArithematicOperatins.sh
# PURPOSE: Add,Sub,Mpy,Mod,Div operations of two numbers.

clear #Clears Screen

Bold=\"\\033\" #Storing escape sequences in a variable.
Normal=\"\\033\"

echo -e \"$Bold Arithmetic Operations Using Linux Shell Programming $Normal\ \"

items=\"
        1-----------ADD
        2-----------SUB
        3-----------MPY
        4-----------MOD
        5-----------DIV
        6-----------EXIT\"

choice=

# simply remove functions and its entries from main script.

exit_function()
{
clear
exit
}

#Function enter is used to go back to menu and clears screen

enter()
{
   unset num1 num2
   ans=
   echo \"\"
   echo -e \"Do you want to continue(y/n):\\c\"
   stty -icanon min 0 time 0

# When -icanon is set then one character has been received.
# min 0 means that read should read 0 characters.
# time 0 ensures that read is terminated the moment one character
# is hit.

while [ -z \"$ans\" ]
do
read ans
done

#The while loop ensures that so long as at least one character is not received read continue to get executed

if [ \"$ans\" = \"y\" -o \"$ans\" = \"Y\" ]
then
   stty sane          # Restoring terminal settings
   clear
else
   stty sane
   exit_function
fi
}

while true
do
   echo -e \"$Bold \\t   Main   MENU $Normal\ \"
   echo -e \"\\t$items \ \"
   echo -n \"Enter your choice : \"
   read choice

   case $choice in
     1) clear
        echo \"Enter two numbers for ADD : \"
        echo -n \"Number1: \"
        read num1
        echo -n \"Number2: \"
        read num2
        echo \"$num1 + $num2 = `expr $num1 + $num2`\"
        enter ;;
     2) clear
        echo \"Enter two numbers for SUB : \"
        echo -n \"Number1: \"
        read num1
        echo -n \"Number2: \"
        read num2
        echo \"$num1 - $num2 = $((num1-num2))\"
        enter ;;
     3) clear
        echo \"Enter two numbers for MPY : \"
        echo -n \"Number1: \"
        read num1
        echo -n \"Number2: \"
        read num2
        echo \"$num1 * $num2 = `echo \"$num1*$num2\"|bc`\"
        enter ;;
     4) clear
        echo \"Enter two numbers for MOD : \"
        echo -n \"Number1: \"
        read num1
        echo -n \"Number2: \"
        read num2
        echo \"$num1 % $num2 = `echo \"$num1%$num2\"|bc`\"
        enter ;;
    5) clear
        echo \"Enter two numbers for DIV : \"
        echo -n \"Number1: \"
        read num1
        echo -n \"Number2: \"
        read num2
        let div=num1/num2
        echo \"$num1 / $num2 = $div\"
        enter ;;
    6) exit_function ;;
    *) echo \"You entered wrong option, Please enter 1,2,3,4,5 or 6\"
        echo \"Press enter to continue\"
        read
        clear
   esac