Linux 系统更换软件源

  由于 linux 系统的默认软件源是系统的官方源，且都在国外，对于国内的用户来说下载非常慢，因此可以通过更换成国内的软件源来进行提速。国内有企业的镜像仓库，例如，阿里云、腾讯云、华为云等，还有国内高校，例如清华大学、中国科学技术大学、浙江大学等都有各自的仓库，都是通过同步官方的软件到各自的仓库来提供加速服务。
  由于 Centos 的最后一个版本 Centos7 也将终止维护，因此不建议安装 Centos 作为服务器，个人推荐 Ubuntu 系统。

Ubuntu 系统

1. 备份官方软件源
   sudo cp /etc/apt/sources.list /etc/apt/sources.list.backup
2. 无安装 vim 编辑器的，执行
   sudo vi /etc/apt/sources.list
   有安装 vim 编辑器的，执行：
   sudo vim /etc/apt/sources.list
3. 将所有未注释的配置注释或者删除
4. 将对应版本的镜像源复制粘贴到 sources.list （以阿里云镜像源为例，其他源类似）
5. 更换源后记得更新一下源和软件
   sudo apt-get update && sudo apt-get upgrade
6. 如果出现依赖问题，执行
   sudo apt-get -f install

Ubuntu 14.04

deb https://mirrors.aliyun.com/ubuntu/ trusty main restricted universe multiverse
deb-src https://mirrors.aliyun.com/ubuntu/ trusty main restricted universe multiverse
deb https://mirrors.aliyun.com/ubuntu/ trusty-security main restricted universe multiverse
deb-src https://mirrors.aliyun.com/ubuntu/ trusty-security main restricted universe multiverse

deb https://mirrors.aliyun.com/ubuntu/ trusty-updates main restricted universe multiverse
deb-src https://mirrors.aliyun.com/ubuntu/ trusty-updates main restricted universe multiverse

deb https://mirrors.aliyun.com/ubuntu/ trusty-backports main restricted universe multiverse
deb-src https://mirrors.aliyun.com/ubuntu/ trusty-backports main restricted universe multiverse

## Not recommended
# deb https://mirrors.aliyun.com/ubuntu/ trusty-proposed main restricted universe multiverse
# deb-src https://mirrors.aliyun.com/ubuntu/ trusty-proposed main restricted universe multiverse

Ubuntu 16.04

deb http://mirrors.aliyun.com/ubuntu/ xenial main
deb-src http://mirrors.aliyun.com/ubuntu/ xenial main

deb http://mirrors.aliyun.com/ubuntu/ xenial-updates main
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-updates main

deb http://mirrors.aliyun.com/ubuntu/ xenial universe
deb-src http://mirrors.aliyun.com/ubuntu/ xenial universe
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates universe
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-updates universe

deb http://mirrors.aliyun.com/ubuntu/ xenial-security main
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-security main
deb http://mirrors.aliyun.com/ubuntu/ xenial-security universe
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-security universe

Ubuntu 18.04

deb http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse

deb http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse

deb http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse

deb http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse

deb http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse

Ubuntu 20.04

deb http://mirrors.aliyun.com/ubuntu/ focal main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ focal main restricted universe multiverse

deb http://mirrors.aliyun.com/ubuntu/ focal-security main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ focal-security main restricted universe multiverse

deb http://mirrors.aliyun.com/ubuntu/ focal-updates main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ focal-updates main restricted universe multiverse

deb http://mirrors.aliyun.com/ubuntu/ focal-proposed main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ focal-proposed main restricted universe multiverse

deb http://mirrors.aliyun.com/ubuntu/ focal-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ focal-backports main restricted universe multiverse