lit. a brick as a door knocker (idiom); fig. a temporary expedient; to use sb as a stepping stone to fortune
（名）比喻以求取名利的初步手段。
偏正式；作宾语；比喻借以谋取名利的工具
敲门的砖石，门敲开后就被抛弃。比喻骗取名利的初步的工具。
宋·曾敏行《独醒杂志》卷五：“一日，冲元自窗外往来，东坡问：‘何为？’冲元曰：‘绥来。’东坡曰：‘可谓奉大福以来绥。’盖冲元登科时赋句也。冲元曰：‘敲门瓦砾，公尚记忆耶！’”