Question

Build a bash script in Unix to simulate a calculator.

It should behave like this:

Enter numone: 4

  Enter operator: +

Enter numtwo: 4

4 + 4 = 8

  Enter operator: -

Enter numtwo: 4

8 - 4 = 4

  Enter operator: MS

4 -> M

  Enter operator: *

Enter numtwo: -2

4 * -2 = -8

  Enter operator: C

results cleared

Program ends once "exit" is entered.

It will work like regular calculator which will only ask for first operand once. The result from previous calculation will become the value for first operand.

Answer 1

# !/bin/bash 
  
# Take user Input 
operator="X"
echo "Enter first number : "
read a 


while true; do  

echo "Enter operator:"
read operator

if [ "$operator" != "exit" ];
then
        echo "Enter second number:"
        read b
fi
case $operator in
  "+")res=`echo $a + $b | bc`
  ;; 
  "-")res=`echo $a - $b | bc` 
  ;; 
  "*")res=`echo $a \* $b | bc` 
  ;; 
  "/")res=`echo "scale=2; $a / $b" | bc` 
  ;; 
  "exit") exit 0 
  ;; 
esac
echo "Result : $res"

a=$res

done