systemctl管理服务的启动，重启，停止，重载，查看状态的命令
| Systcinit命令(红帽RHEL6系统) | Systemctl命令(红帽RHEL7系统) | 作用 |
| service foo start | systemctl start foo.service | 启动服务 |
| service foo restart | systemctl restart foo.service | 重启服务 |
| service foo stop | systemctl stop foo.service | 停止服务 |
| service foo reload | systemctl reload foo.service | 重新加载配置文件(不终止服务) |
| service foo status | systemctl status foo.service | 查看服务状态 |
systemctl设置服务的开机启动，不启动，查看各级别下服务启动状态的命令
| Sysvinit命令(红帽RHEL6系统) | Systemctl命令(红帽RHEL7系统) | 作用 |
| chkconfig foo on | systemctk enable foo.service | 开机自动启动 |
| chkconfig foo off | systemctl disable foo.service | 开机不自动启动 |
| chkconfig foo | systemctl is-enabled foo.service | 查看特定服务是否为开机自启动 |
| chkconfig --list | systemctl list-unit-files --type=service | 查看各个级别下服务的启动与禁用情况 |