systemctl命令是系统服务管理指令，它实际上是将service和chkconfig两个命令组合到一起。
| 任务 | 旧指令 | 新指令 |
| 使某服务自动启动 | chkconfig --level 3 httpd on | systemctl enable httpd.service |
| 使某服务不自动启动 | chkconfig --level 3 httpd off | ystemctl disable httpd.service |
| 检查某服务状态 | service httpd status |
systemctl status httpd.service(显示服务详细信息) systemctl is -active httpd.service(仅显示是否Active) |
| 显示所有已启动的服务 | chkconfig --list | systemctl list-units --type=service |
| 启动某服务 | service httpd start | systemctl start httpd.service |
| 停止某服务 | service httpd stop | systemctl stop httpd.service |
| 重启某服务 | service httpd restart | systemctl restart httpd.service |