centos7，趋势
systemctl list-units --all --type=service
列出信息
空格往下翻，会看到解释
LOAD = Reflects whether the unit definition was properly loaded.
ACTIVE = The high-level unit activation state, i.e. generalization of SUB. inactice :未激活 actice ：激活 ，DESCRIPTION：一些解释信息
SUB = The low-level unit activation state, values depend on unit type.
几个常用的服务相关的命令
systemctl enable crond.service //让服务开机启动
systemctl disable crond //不让开机启动
systemctl status crond //查看状态
systemctl stop crond //停止服务
systemctl start crond //启动服务
systemctl restart crond //重启服务
systemctl is-enabled crond //检查服务是否开机启动
文件源路径：/usr/lib/systemd/system/
linux-日常运维-服务管理-systemd
原文：http://blog.51cto.com/13451715/2310938
