【shell】shell腳本，輸入一個數字n並計算1~n的和。要求：輸入的數字大於1

#!/bin/bash


while :
sum=0
do

        read -p "please enter a num,num must greater than 1>>" num
        if test  $[num] -gt 1
        then
                for i in `seq 1 ${num}`
                do
                        sum=$[${i}+${sum}]
                        #echo ${i}
                done
        printf "1 to %s sum is: %s \n" ${num} ${sum}
        break

        else
        echo your enter has error!!
        fi

done