在Clojure中拖拽文件? [英] Tailing a file in Clojure?
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问题描述
在Clojure中拖放文件的最好方法是什么?我没有遇到任何有助于这样做的实用程序,但是关于如何构建一个的实用程序将非常感激。
What would be the best method to tail a file in Clojure? I haven't come across any utilities that would help do so, but ideas on how to build one would be appreciated!
谢谢。
推荐答案
如 kotarak 所述,您可以使用 RandomAccessFile 搜索文件结尾。不幸的是,你必须忙等待/睡眠的变化。
As kotarak stated, you could use RandomAccessFile to seek to the end of the File. Unfortunately you have to busy-wait/sleep for changes.
使用延迟序列,您可以处理即时行:
Using a lazy sequence you can process the lines "on-the-fly":
(import java.io.RandomAccessFile)
(defn raf-seq
[#^RandomAccessFile raf]
(if-let [line (.readLine raf)]
(lazy-seq (cons line (raf-seq raf)))
(do (Thread/sleep 1000)
(recur raf))))
(defn tail-seq [input]
(let [raf (RandomAccessFile. input "r")]
(.seek raf (.length raf))
(raf-seq raf)))
; Read the next 10 lines
(take 10 (tail-seq "/var/log/mail.log"))
更新:
像 tail -f /var/log/mail.log -n 0 em> doseq ,因此更改实际上已消耗。
Something like tail -f /var/log/mail.log -n 0, using doseq, so the changes are actually consumed.
(doseq [line (tail-seq "/var/log/mail.log")] (println line))
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