Write a shell script to generate mark sheet of a student. Take 3 subjects, calculate and display total marks, percentage and Class obtained by the student. - OS

echo "Enter the five subject marks for the student"
read s1 s2 s3
sum1=`expr $s1 + $s2 + $s3`
echo "Sum of 5 subjects are: " $sum1
per=`expr $sum1 / 3`
echo " Percentage: " $per
if [ $per -ge 60 ]
then
echo "You get Distinction"
elif [ $per -ge 50 ]
then
echo You get First class
elif [ $per -ge 40 ]
then
echo "You get Second class"
else
echo "You get Fail"
fi