显示进度条（回旋镖版）

#!/bin/bash 
while :
do
clear
for i in {1..20}
do
   echo ‐e "\033[3;${i}H*"
   sleep 0.1
done
clear
for i in {20..1}
do
   echo ‐e "\033[3;${i}H*"
   sleep 0.1
done
clear
done