docker nginx apt-get不能更新问题

cd /etc/apt
touch  sources.list
echo "deb http://mirrors.ustc.edu.cn/debian stable main contrib non-free" >>sources.list
echo "deb http://mirrors.ustc.edu.cn/debian stable-updates main contrib non-free" >>sources.list


root@91f083c6fd50:/etc/apt# cat sources.list
deb http://mirrors.ustc.edu.cn/debian stable main contrib non-free
deb http://mirrors.ustc.edu.cn/debian stable-updates main contrib non-free

apt-get update
apt-get install vim
root@91f083c6fd50:/etc/apt# which vim
/usr/bin/vim