ubuntu 22.04 系统更换镜像源

前言

适用于 Ubuntu 22.04 之后的操作系统

ubuntu系统默认官方源（archive.ubuntu.com）通常位于国外，国内用户访问时网络延迟高、带宽受限，导致下载软件速度很慢或者直接遇到更新失败，更换Ubuntu系统的镜像源可以告别蜗牛更新而且可以保证超强稳定性；国内常用的ubuntu镜像源主要包括阿里云、清华大学、中科大、网易等

操作步骤

1. 查看操作系统版本，便于选择对应的源：

   lsb_release -a

2. 备份源列表：

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

3. ubuntu 22.04 LTS (jammy) 配置如下：

   deb https://mirrors.aliyun.com/ubuntu/ jammy main restricted universe multiverse
   deb-src https://mirrors.aliyun.com/ubuntu/ jammy main restricted universe multiverse
    
   deb https://mirrors.aliyun.com/ubuntu/ jammy-security main restricted universe multiverse
   deb-src https://mirrors.aliyun.com/ubuntu/ jammy-security main restricted universe multiverse
    
   deb https://mirrors.aliyun.com/ubuntu/ jammy-updates main restricted universe multiverse
   deb-src https://mirrors.aliyun.com/ubuntu/ jammy-updates main restricted universe multiverse
    
   # deb https://mirrors.aliyun.com/ubuntu/ jammy-proposed main restricted universe multiverse
   # deb-src https://mirrors.aliyun.com/ubuntu/ jammy-proposed main restricted universe multiverse
    
   deb https://mirrors.aliyun.com/ubuntu/ jammy-backports main restricted universe multiverse
   deb-src https://mirrors.aliyun.com/ubuntu/ jammy-backports main restricted universe multiverse

4. ubuntu 20.04 LTS (focal) 配置如下：

   deb https://mirrors.aliyun.com/ubuntu/ focal main restricted universe multiverse
   deb-src https://mirrors.aliyun.com/ubuntu/ focal main restricted universe multiverse
    
   deb https://mirrors.aliyun.com/ubuntu/ focal-security main restricted universe multiverse
   deb-src https://mirrors.aliyun.com/ubuntu/ focal-security main restricted universe multiverse
    
   deb https://mirrors.aliyun.com/ubuntu/ focal-updates main restricted universe multiverse
   deb-src https://mirrors.aliyun.com/ubuntu/ focal-updates main restricted universe multiverse
    
   # deb https://mirrors.aliyun.com/ubuntu/ focal-proposed main restricted universe multiverse
   # deb-src https://mirrors.aliyun.com/ubuntu/ focal-proposed main restricted universe multiverse
    
   deb https://mirrors.aliyun.com/ubuntu/ focal-backports main restricted universe multiverse
   deb-src https://mirrors.aliyun.com/ubuntu/ focal-backports main restricted universe multiverse

5. 执行sudo apt update 以更新软件包索引，若不执行该指令则继续使用旧源的软件包列表，无法获取新内容，该指令并不会更新系统中任何已安装的软件包：

   sudo apt update