Ubuntu在树莓派上启动时间特别长，通过命令systemd-analyze blame分析发现有两个服务apt-daily-upgrade.service和apt-daily.service的启动时间有些长。
有几种修改方式，一是禁用服务，操作如下：
systemctl disable apt-daily.service
systemctl disable apt-daily.timer
systemctl disable apt-daily-upgrade.timer
systemctl disable apt-daily-upgrade.service