start NAME... Start (activate) one or more units(開啟服務)
restart Start or restart one or more units(重啟服務)
stop NAME... Stop (deactivate) one or more units(關閉服務)
enable NAME... Enable one or more unit files(開機載入)
disable NAME... Disable one or more unit files(開機進用)status [PATTERN...|PID...] Show runtime status of one or more units(服務狀態)
reload NAME... Reload one or more units(重新載入設定)
get-default 顯示目前系統預設運作層級
list-unit-files 列出全部服務
isolate 切換運作層級
multi-user.target (3)
graphical.target (5)
