【shell】1加到100的方法

n=1
sum=0

while [ $n -le 100 ]
do
        #let sum+=n
        #sum=$(($sum+$n))
        sum=$[$sum+$n]

        #let n++
        #n=$(($n+1))
        n=$[$n+1]
done
echo $sum

sum=0
for n in {
    1..100}
do
        let sum+=n
done
echo $sum