Ubuntu 使用 unattended-upgrades 工具來實現自動更新，包括安全更新、常規更新和 backports。該工具可以自動下載并安裝更新，并配置為自動清理舊包或重啟系統（如果需要）。
sudo apt update
sudo apt install unattended-upgrades
sudo nano /etc/apt/apt.conf.d/50unattended-upgrades
Unattended-Upgrade::Allowed-Origins {"${distro_id}:${distro_codename}";"${distro_id}:${distro_codename}-security";"${distro_id}ESM:${distro_codename}";};
Unattended-Upgrade::Remove-Unused-Dependencies "true";
sudo nano /etc/apt/apt.conf.d/20auto-upgrades
APT::Periodic::Update-Package-Lists "1";
APT::Periodic::Download-Upgradeable-Packages "1";
APT::Periodic::AutocleanInterval "7";
APT::Periodic::Unattended-Upgrade "1";
sudo unattended-upgrades --dry-run --debug
自動更新的日志會保存在 /var/log/unattended-upgrades/ 目錄下。
