倒计时脚本！

#!/bin/bash
#作者：博客鱼
echo "倒计时"
read -p "请输入倒计时时间的分钟数:" aa
read -p "请输入倒计时的秒数:" bb
i=aa*60+bb
for ((time=$i;time>0;time--))
do
a=$[$time/60]
b=$[$time%60]
echo -ne "\r$a:$b \r"
sleep 1
done