镜像源配置

1. 备份原配置文件

   sudo cp /etc/apt/sources.list /etc/apt/sources.list.bak

2. 修改sources.list文件

   sudo vim /etc/apt/source.list

   使用sudo vim /etc/apt/source.list打开文件，将文件原内容删除，添加在清华源获取的内容

3. 更新软件列表和软件源

   sudo apt-get update
   sudo apt-get upgrade

4. 国内软件源

   中国科学大学软件源、阿里云软件源

   清华软件源

   # 默认注释了源码镜像以提高 apt update 速度，如有需要可自行取消注释
   deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal main restricted universe multiverse
   # deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal main restricted universe multiverse
   deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-updates main restricted universe multiverse
   # deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-updates main restricted universe multiverse
   deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-backports main restricted universe multiverse
   # deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-backports main restricted universe multiverse
   
   # 以下安全更新软件源包含了官方源与镜像站配置，如有需要可自行修改注释切换
   deb http://security.ubuntu.com/ubuntu/ focal-security main restricted universe multiverse
   # deb-src http://security.ubuntu.com/ubuntu/ focal-security main restricted universe multiverse
   
   # 预发布软件源，不建议启用
   # deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-proposed main restricted universe multiverse
   # # deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-proposed main restricted universe multiverse

5. 脚本一键配置apt源

   #!/bin/bash
   #更新apt源为清华源
   echo "[Info] 正在备份默认apt源..."
   cp /etc/apt/sources.list /etc/apt/sources.list.bak
   echo "[Info] 正在替换apt源为清华apt源..."
   echo deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic main restricted universe multiverse > /etc/apt/sources.list
   echo deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse >> /etc/apt/sources.list
   echo deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse >> /etc/apt/sources.list
   echo deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-security main restricted universe multiverse >> /etc/apt/sources.list
   echo "[Info] 正在更新源..."
   apt update
   echo "[Info] 正在更新软件..."
   apt upgrade -y