calculator.sh

#!/bin/bash
Error() {
    echo "[ FAIL ] 잘못된 번호를 입력했습니다."
    exit 1
}
echo -n "Enter A : "
read A
echo -n "Enter  OP : "
read OP
echo -n "Enter B : "
read B

case $OP in
    '+') echo "$A + $B = $(expr $A + $B)"   ;;
    '-') echo "$A - $B = $(expr $A - $B)"   ;;
    '*') echo "$A x $B = $(expr $A \* $B)"  ;;
    '/') echo "$A / $B = $(expr $A / $B)"   ;;
    *  ) Error          ;;
esac