启动服务：systemctl start vsftpd.service
关闭服务：systemctl stop vsftpd.service
重启服务：systemctl restart vsftpd.service
显示服务的状态：systemctl status vsftpd.service
在开机时启用服务：systemctl enable vsftpd.service
在开机时禁用服务：systemctl disable vsftpd.service
查看服务是否开机启动：systemctl is-enabled vsftpd.service
查看已启动的服务列表：systemctl list-unit-files|grep enabled
查看启动失败的服务列表：systemctl --failed
centos8 ：
查看防火墙状态：systemctl status firewalld.service
开启防火墙：systemctl start firewalld.service
关闭防火墙：systemctl stop firewalld.service
禁用防火墙：systemctl disable firewalld.service
systemctl service update-rc.d三者的区别