我的Bash脚本工作不正常

Question

我正在制作一个bash脚本，显示基于用户输入的等级。但是，它正在返回错误的等级，我无法弄清楚为什么。我发布了下面的代码。我对bash脚本也很陌生。

#!/bin/bash 

echo "Enter assignment mark (0 to 40): " 
read assignment 
echo "Enter Test1 mark (0 to 15): " 
read test1 
echo "Enter Test2 mark (1 to 15): " 
read test2 
echo "Enter Final Exam mark (1 to 30): " 
read final 

((sum = ($assignment/40 * 40) + ( $test1/15 *15) + ($test2/15 * 15) + ($final/30 * 30))) 

if [ $sum -ge "90" ] && [ $sum -le "100" ] 
then 
echo "Your final grade is an A+." 
elif [ $sum -ge "85" ] && [ $sum -le "89" ] 
then 
echo "Your final grade is a A." 
elif [ $sum -ge "80" ] && [ $sum -le "84" ] 
then 
echo "Your final grade is a A-." 
elif [ $sum -ge "77" ] && [ $sum -le "79" ] 
then 
echo "Your final grade is a B+." 
elif [ $sum -ge "73" ] && [ $sum -le "76" ] 
then 
echo "Your final grade is a B." 
elif [ $sum -ge "70" ] && [ $sum -le "72" ] 
then 
echo "Your final grade is a B-." 
elif [ $sum -ge "67" ] && [ $sum -le "69" ] 
then 
echo "Your final grade is a C+." 
elif [ $sum -ge "63" ] && [ $sum -le "66" ] 
then 
echo "Your final grade is a C." 
elif [ $sum -ge "60" ] && [ $sum -le "62" ] 
then 
echo "Your final grade is a C-." 
elif [ $sum -ge "57" ] && [ $sum -le "59" ] 
then 
echo "Your final grade is a D+." 
elif [ $sum -ge "53" ] && [ $sum -le "56" ] 
then 
echo "Your final grade is an D." 
elif [ $sum -ge "50" ] && [ $sum -le "52" ] 
then 
echo "Your final grade is an D-." 
elif [ $sum -le "49" ] 
then 
echo "Your final grade is an F. Sorry!" 
fi 

Answer 1

我不明白这行：

((sum = ($assignment/40 * 40) + ( $test1/15 *15) + ($test2/15 * 15) + ($final/30 * 30))) 

划分和相同数量的倍增，似乎是无用的。为什么不改变它

((sum = $assignment + $test1 + $test2 + $final)) 

编辑：此代码的工作原理。享受;-)

#!/bin/bash 

echo "Enter assignment mark (0 to 40): " 
read assignment 
echo "Enter Test1 mark (0 to 15): " 
read test1 
echo "Enter Test2 mark (1 to 15): " 
read test2 
echo "Enter Final Exam mark (1 to 30): " 
read final 

sum=$((assignment + test1 + test2 + final )) 

if [[ $sum -ge 90 ]] && [[ $sum -le 100 ]] 
then 
echo Your final grade is an A+. 
elif [[ $sum -ge 85 ]] && [[ $sum -le 89 ]] 
then 
echo Your final grade is a A. 
elif [[ $sum -ge 80 ]] && [[ $sum -le 84 ]] 
then 
echo Your final grade is a A-. 
elif [[ $sum -ge 77 ]] && [[ $sum -le 79 ]] 
then 
echo Your final grade is a B+. 
elif [[ $sum -ge 73 ]] && [[ $sum -le 76 ]] 
then 
echo Your final grade is a B. 
elif [[ $sum -ge 70 ]] && [[ $sum -le 72 ]] 
then 
echo Your final grade is a B-. 
elif [[ $sum -ge 67 ]] && [[ $sum -le 69 ]] 
then 
echo Your final grade is a C+. 
elif [[ $sum -ge 63 ]] && [[ $sum -le 66 ]] 
then 
echo Your final grade is a C. 
elif [[ $sum -ge 60 ]] && [[ $sum -le 62 ]] 
then 
echo Your final grade is a C-. 
elif [[ $sum -ge 57 ]] && [[ $sum -le 59 ]] 
then 
echo Your final grade is a D+. 
elif [[ $sum -ge 53 ]] && [[ $sum -le 56 ]] 
then 
echo Your final grade is an D. 
elif [[ $sum -ge 50 ]] && [[ $sum -le 52 ]] 
then 
echo Your final grade is an D-. 
elif [[ $sum -le 49 ]] 
then 
echo Your final grade is an F. Sorry! 
fi