使用官方的Ubuntu源速度非常的慢，每次修改軟件源的時候都要上網搜，所以乾脆寫個文章存下來，自己找起來也方便，Mark一下。
修改Ubuntu源的方式
- 首先備份默認源文件sources.list爲sources.list.bak
sudo cp -a /etc/apt/sources.list /etc/apt/sources.list.bak - 新建名爲sources.list的文件，並且根據自己的需要選擇下面不同的源使用
一點說明
以 xenial 爲例，其它版本替換成相應版本號即可（可以用 lsb_release -a 查看當前版本代號）。
請根據需要去掉 deb-src 以及 backports 和 proposed-updates 前面的註釋
阿里源
deb http://mirrors.aliyun.com/ubuntu/ xenial main restricted universe multiverse
# deb-src http://mirrors.aliyun.com/ubuntu/ xenial main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted universe multiverse
# deb-src http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted universe multiverse
# deb-src http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted universe multiverse
# deb http://mirrors.aliyun.com/ubuntu/ xenial-proposed main restricted universe multiverse
# deb-src http://mirrors.aliyun.com/ubuntu/ xenial-proposed main restricted universe 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清華大學源
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial main multiverse restricted universe
# deb-src http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial main multiverse restricted universe
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security main multiverse restricted universe
# deb-src 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-updates main multiverse restricted universe
# deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-backports main multiverse restricted universe
# deb-src 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-src http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-proposed main multiverse restricted universe西安電子科技大學源
西電源僅校園網內可用：
deb http://linux.xidian.edu.cn/mirrors/ubuntu/ xenial main restricted universe multiverse
#deb-src http://linux.xidian.edu.cn/mirrors/ubuntu/ xenial main restricted universe multiverse
deb http://linux.xidian.edu.cn/mirrors/ubuntu/ xenial-security main restricted universe multiverse
#deb-src http://linux.xidian.edu.cn/mirrors/ubuntu/ xenial-security main restricted universe multiverse
deb http://linux.xidian.edu.cn/mirrors/ubuntu/ xenial-updates main restricted universe multiverse
#deb-src http://linux.xidian.edu.cn/mirrors/ubuntu/ xenial-updates main restricted universe multiverse
#deb http://linux.xidian.edu.cn/mirrors/ubuntu/ xenial-backports main restricted universe multiverse
#deb-src http://linux.xidian.edu.cn/mirrors/ubuntu/ xenial-backports main restricted universe multiverse
#deb http://linux.xidian.edu.cn/mirrors/ubuntu/ xenial-proposed main restricted universe multiverse
#deb-src http://linux.xidian.edu.cn/mirrors/ubuntu/ xenial-proposed main restricted universe multiverse