#!/bin/bash

# 1. 先备份原 sources.list
echo "正在备份原软件源..."
sudo mv /etc/apt/sources.list /etc/apt/sources.list.bak

# 2. 直接写入清华源（无交互，无需nano）
echo "正在写入清华大学镜像源..."
sudo bash -c 'cat > /etc/apt/sources.list << EOF
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-updates main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-backports main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-security main restricted universe multiverse
EOF'

# 3. 更新软件源
echo "正在更新 apt 软件源..."
sudo apt update -y

echo -e "\n✅ 切换 Ubuntu 22.04 清华源完成！"