配置ubuntu代码源

配置 Ubuntu 的软件源可以通过以下步骤完成：

1. 打开终端，输入以下命令备份原有的源列表文件：

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

2. 编辑源列表文件，选择合适的源地址，例如使用阿里云的源：

   sudo vim /etc/apt/sources.list

在文件中添加以下内容：

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

3. 更新软件源：

   sudo apt-get update

4. 完成。