I have the below UNIX code:

#!/bin/bash

while true

do

if [[ $# -eq 0 ]] ; then

if [[ $result == "" ]]; then # check if $result is empty

echo Enter operand1 value:

read operand1

else

operand1=$result # if not empty then assign its value to $operand1

echo "Operand 1 is: $result"

echo ""

fi

# Offer choices

echo 1. Addition

echo 2. Subtraction

echo 3. Multiplication

echo 4. Division

echo 5. Exit

echo MR

echo 7. MS

echo 8. MC

echo 9. M+

echo 10. Clear

echo Enter your choice:

read choice

if [[ $choice != 1 && $choice != 2 && $choice != 3 && $choice != 4 && $choice != 5 && $choice != MR ]] ; then

echo Sorry $choice is not a valid operator - please try again

echo Enter your choice:

read choice

fi

echo Enter operand2 value:

read operand2

# get operands and start computing based on the user's choice

if [[ $choice -eq 1 ]] ; then

result=$((operand1+operand2)) # store result

echo ----------------------------------------

echo Addition of $operand1 and $operand2 is $((operand1+operand2))

echo ----------------------------------------

echo

elif [[ $choice -eq 2 ]] ; then

result=$((operand1-operand2)) # store result

echo ----------------------------------------

echo Subtraction of $operand1 and $operand2 is $((operand1-operand2))

echo ----------------------------------------

echo

elif [[ $choice -eq 3 ]] ; then

result=$((operand1*operand2)) # store result

echo ----------------------------------------

echo Multiplication of $operand1 and $operand2 is $((operand1*operand2))

echo ----------------------------------------

echo

elif [[ $choice -eq 4 && operand2 -eq 0 ]] ; then

echo Can not divide by 0 please try again

echo Please enter operand2

read operand2

echo ----------------------------------------

echo Division of $operand1 and $operand2 is $((operand1/operand2))

echo ----------------------------------------

echo

result=$((operand1/operand2)) # store result

elif [[ $choice -eq 4 && operand2 -ne 0 ]] ; then

result=$((operand1/operand2)) # store result

echo ----------------------------------------

echo Division of $operand1 and $operand2 is $((operand1/operand2))

echo ----------------------------------------

echo

elif [[ $choice -eq 5 ]] ; then

exit

elif [[ $choice || $operand1 || $operand2 -eq MR ]] ; then

echo MR $result

else

echo ----------------------------------------

echo Invalid choice.. Please try again

echo ----------------------------------------

echo

fi

else

echo ----------------------------------------

echo You either passed too many parameters or too less

echo than the optimum requirement.

echo

echo This program accepts a maximum of 2 arguments or no

echo argument at all in order to run successfully.

echo ----------------------------------------

fi

done

I have attempted to add functionality that include MR, MS, MC and M+ although I have been struggling to add it in. Would someone be able to help with this?

The requirement is to have a calculator which asks a user an operand then the operator then the second operand. The calculator is to operate so that the result is always stored. Meaning that the user will not have to enter the first operand as it will simply be from the previous result. I have everything but the functionality for MR, MS, MC M+ and clear set up so that it runs I just need to implement this functionality which I am stuck on.