systemctl start postfix.service關閉一個服務：systemctl stop postfix.service重啟一個服務：systemctl restart postfix.service顯示一個服務的狀態：systemctl status postfix.service在開機時啟用一個服務：systemctl enable postfix.service在開機時禁用一個服務：systemctl disable postfix.service查看服務是否開機啟動：systemctl is-enabled postfix.service查看已啟動的服務列表：systemctl list-unit-files|grep enabled查看啟動失敗的服務列表：systemctl --failed新聞熱點
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