使用官方的Ubuntu源速度非常的慢，每次修改软件源的时候都要上网搜，所以干脆写个文章存下来，自己找起来也方便，Mark一下。
修改Ubuntu源的方式
- 首先备份默认源文件sources.list为sources.list.bak
sudo cp -a /etc/apt/sources.list /etc/apt/sources.list.bak - 新建名为sources.list的文件，并且根据自己的需要选择下面不同的源使用
一点说明
以 xenial 为例，其它版本替换成相应版本号即可（可以用 lsb_release -a 查看当前版本代号）。
请根据需要去掉 deb-src 以及 backports 和 proposed-updates 前面的注释
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清华大学源
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西安电子科技大学源
西电源仅校园网内可用：
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