先备份原始源，再替换为阿里云源即可。
Ubuntu 26.04（Resolute Raccoon）默认已经使用 .sources 格式，而不是老的 sources.list。
1. 备份原配置
sudo cp /etc/apt/sources.list.d/ubuntu.sources /etc/apt/sources.list.d/ubuntu.sources.bak
2. 编辑镜像源
sudo vim /etc/apt/sources.list.d/ubuntu.sources
将内容替换为：
Types: deb
URIs: https://mirrors.aliyun.com/ubuntu/
Suites: resolute resolute–updates resolute–backports
Components: main restricted universe multiverse
Signed-By: /usr/share/keyrings/ubuntu–archive–keyring.gpg
Types: deb
URIs: https://mirrors.aliyun.com/ubuntu/
Suites: resolute–security
Components: main restricted universe multiverse
Signed-By: /usr/share/keyrings/ubuntu–archive–keyring.gpg
3. 更新缓存
sudo apt update
4. 验证是否生效
apt policy
或者：
grep -E "mirrors.aliyun.com" /etc/apt/sources.list.d/ubuntu.sources
一键脚本（推荐）
直接执行：
sudo bash -c 'cat > /etc/apt/sources.list.d/ubuntu.sources <<EOF
Types: deb
URIs: https://mirrors.aliyun.com/ubuntu/
Suites: resolute resolute-updates resolute-backports
Components: main restricted universe multiverse
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg
Types: deb
URIs: https://mirrors.aliyun.com/ubuntu/
Suites: resolute-security
Components: main restricted universe multiverse
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg
EOF'
sudo apt update
