这只是一个现实需求，今天用apt get安装软件的时候，发现其默认使用更新源的IPv6地址，但刚好我这边今天IPv6地址不能用了，所以找了找解决方法，其实很简单，例如这里介绍的：http://blog.sina.com.cn/s/blog_72ef7bea0102vqjj.html，在使用upgrade等命令的时候，强制其使用IPv4地址：
sudo apt -o Acquire::ForceIPv4=true upgrade
另外，更改Ubuntu apt-get更新源为国内的方法：
sudo gedit /etc/apt/sources.list
打开后加上对应源的信息，我常用的几个如下：
中科大源：
deb http://mirrors.ustc.edu.cn/ubuntu/ xenial main restricted universe multiverse deb http://mirrors.ustc.edu.cn/ubuntu/ xenial-security main restricted universe multiverse deb http://mirrors.ustc.edu.cn/ubuntu/ xenial-updates main restricted universe multiverse deb http://mirrors.ustc.edu.cn/ubuntu/ xenial-proposed main restricted universe multiverse deb http://mirrors.ustc.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse deb-src http://mirrors.ustc.edu.cn/ubuntu/ xenial main restricted universe multiverse deb-src http://mirrors.ustc.edu.cn/ubuntu/ xenial-security main restricted universe multiverse deb-src http://mirrors.ustc.edu.cn/ubuntu/ xenial-updates main restricted universe multiverse deb-src http://mirrors.ustc.edu.cn/ubuntu/ xenial-proposed main restricted universe multiverse deb-src http://mirrors.ustc.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse
阿里云源：
deb http://mirrors.aliyun.com/ubuntu/ vivid main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ vivid-security main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ vivid-updates main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ vivid-proposed main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ vivid-backports main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ vivid main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ vivid-security main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ vivid-updates main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ vivid-proposed main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ vivid-backports main restricted universe multiverse
清华源：
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial main multiverse restricted universe deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-backports main multiverse restricted universe deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-proposed main multiverse restricted universe deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security main multiverse restricted universe deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-updates main multiverse restricted universe deb-src http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial main multiverse restricted universe deb-src http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-backports main multiverse restricted universe deb-src http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-proposed main multiverse restricted universe deb-src http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security main multiverse restricted universe deb-src http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-updates main multiverse restricted universe
更改完之后保存，并运行：
sudo apt-get update即可。就简单记录这么多。