Question

编写一个 Shell 程序，计算从1到用户输入数字的和。(1+2+3+…n)

Answer 1

#! /bin/bash
read -p "Enter a num: " num
sum=0
for i in $(seq $num)
do
sum=$((sum + i))
done
echo "Sum is $sum"

Answer 2

#! /bin/bash
#jisuan1 jisuan cong 1jia dao n de zhi
echo -n "Please Input number : "
read SHU
sum=0
for((j=1;j<=$SHU;j++))
do
sum=` expr $sum + $j`
done
echo "Sum = $sum"