原文网址：https://www.youyong.top/article/1158e5b639e2
CentOS 7.0 在 /var/log/messages 中发现类似如下报错：
(1) systemd-cgroups-agent: Failed to get D-Bus connection: Failed to connect to socket /run/systemd/private: No such file or directory
(2) systemd: Failed to open private bus connection: Failed to connect to socket /var/run/dbus/system_bus_socket: No such file or directory
