Java在運行時輸出打印輸出

Question

我試圖在Java程序中運行split命令。當我在控制檯參數--verbose運行它，它打印所生成的塊如下：

creating file 'chunk00' 
creating file 'chunk01' 
creating file 'chunk02' 

但是，當我在java程序運行它，這些輸出都將在完成處理後進行印刷。當split進程正在運行時，我必須做些什麼才能獲得輸出？

我用下面的代碼：

ProcessBuilder pb = new ProcessBuilder("split", "-a 2", "-d", "-b 52MB","--verbose",path+"/"+db,"chunk"); 
     pb.redirectErrorStream(true); 
     File workingFolder = new File("/home/hajibaba"); 
     pb.directory(workingFolder); 
     Process proc = pb.start(); 
     BufferedReader stdInput = new BufferedReader(new InputStreamReader(proc.getInputStream())); 

     // read the output from the command 
     String s = null; 
     while ((s = stdInput.readLine()) != null) 
     { 
      System.out.println(s); 
     } 
     proc.waitFor(); 

但是，它適用於使用echo打印相同的結果bash腳本。

Answer 1

I/O在交互式會話中被緩存，但在寫入管道時被緩存。

要解決此問題，可以使用unbuffer命令關閉緩衝。

ProcessBuilder pb = new ProcessBuilder("unbuffer", "split", "-a2", "-d", "-b52MB","--verbose",path+"/"+db,"chunk"); 

https://unix.stackexchange.com/questions/25372/turn-off-buffering-in-pipe