#systemctl --help #查詢systemctl指令用法
#systemctl list-units #查詢目前所有啟動中的服務
#systemctl list-units -a #查詢目前所有已啟動及未啟動的服務
#systemctl enable xxx.service #設定開機啟動xxx.service
#systemctl disable xxx.service #設定開始不啟動xxx.service
#systemctl stop xxx.service #立即停止xxx.service
#systemctl start xxx.service #立即啟動xxx.service
#ssytemctl status xxx.service #查詢xxx.serivce目前的狀態
#systemctl is-active xxx.service #查詢服務是否正常啟動