Java在运行时输出打印输出

Question

我试图在Java程序中运行split命令。当我在控制台参数--verbose运行它，它打印所生成的块如下：

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

但是，当我在java程序运行它，这些输出都将在完成处理后进行印刷。当split进程正在运行时，我必须做些什么才能获得输出？

我用下面的代码：

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，它适用于使用echo打印相同的结果bash脚本。

Answer 1

I/O在交互式会话中被缓存，但在写入管道时被缓存。

要解决此问题，可以使用unbuffer命令关闭缓冲。

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

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