Ubuntu解决apt install 下载速度太慢

之前使用apt install下载软件速度几乎不动，下载速度以B/s计量。
使用如下方法，切换源之后速度飞起，亲测好用，推荐大家。

命令方式
今天在用虚拟机安装编译linux内核所需依赖库的时候，使用 apt-get 指令进行安装速度非常之不稳定，而且大多时候都很慢。原因是其默认源在国外，因此速度自然不会很快。于是换成阿里的源，速度明显快了很多（如果是自身 络问题那就没办法了），以下是换源的步骤。

1.打开终端，首先最好备份一下原来的source文件：sudo cp /etc/apt/sources.list /etc/apt/sources.list.bak 。
2.然后打开source文件，sudo gedit /etc/apt/sources.list，将内容替换为：

#deb cdrom:[Ubuntu 16.04 LTS Xenial Xerus – Release amd64 (20160420.1)]/ xenial main restricted
deb-src http://archive.ubuntu.com/ubuntu xenial main restricted
#Added by software-properties
deb http://mirrors.aliyun.com/ubuntu/ xenial main restricted
deb-src http://mirrors.aliyun.com/ubuntu/ xenial main restricted multiverse universe
#Added by software-properties
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted multiverse universe
#Added by software-properties
deb http://mirrors.aliyun.com/ubuntu/ xenial universe
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates universe
deb http://mirrors.aliyun.com/ubuntu/ xenial multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse
#Added by software-properties
deb http://archive.canonical.com/ubuntu xenial partner
deb-src http://archive.canonical.com/ubuntu xenial partner
deb http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted multiverse universe
#Added by software-properties
deb http://mirrors.aliyun.com/ubuntu/ xenial-security universe
deb http://mirrors.aliyun.com/ubuntu/ xenial-security multiverse

3.执行更新：sudo apt-get update

好了，现在可以愉快的下载想要的软件了。