$ cat /etc/apt/sources.list
#deb-src http://mirrors.aliyun.com/ubuntu/ xenial main restricted universe multiverse
#deb-src http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted universe multiverse
#deb-src http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse
#deb-src http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted universe multiverse
#deb-src http://mirrors.aliyun.com/ubuntu/ xenial-proposed main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-proposed main restricted universe multiverse
上边注释的是:代码源,如果不看源代码的话,可以注释掉,只需要更新包即可。