Java - 如何检查另一个（非Java）进程是否在Linux上运行

问题描述

我们正在使用Xvfb虚拟桌面管理器，并希望确保它在我继续之前运行。使用纯shell，我可以轻松地做到这一点：

  ps -ef | grep Xvfb | grep -v grep 
  

这就给我提供了我需要的东西，一行包含关于Xvfb PROC。接下来，我想将它结合到我的Java程序中，并解析结果并存储正在运行的Xvfb进程的PID。所以我想这样做：

 字符串行; 
尝试{
 Process p = Runtime.getRuntime（）。exec（ps -ef | grep Xvfb | grep -v grep）; 
 BufferedReader input = new BufferedReader（new InputStreamReader（p.getInputStream（）））; （（line = input.readLine（））！= null）
 
 {
 System.out.println（line）; 
} 
} catch（Exception err）{
 System.out.println（err）; 
 
 $ / code> 

奇怪的是，如果我使用ps -ef当我运行我的应用程序时，大量的进程转储到我的控制台。但是如果我使用| grep来缩小返回的进程列表，我得到零结果。 input.readLine（）每次都会返回null。

我也试过：

  ps -ef | grep Xvfb | grep -v grep | awk {'print $ 2'} 
  

只需获取进程ID。

有没有其他人经历过这样的事情，或者知道我做错了什么？

解决方案

您试图使用|这是shell特有的管道功能，因此你不能在java进程中执行它。您可以尝试使用 pidof Xvfb 来获取进程ID。

I'm having some weird problems with this.

We are using Xvfb virtual desktop manager and want to make sure it's running before I continue. Using pure shell, I could do this easily:

    ps -ef | grep Xvfb | grep -v grep

And that gives me exactly what I need, a single line containing information about the Xvfb proc. Next, I want to incorporate this into my Java program and parse the results and store the PID of the running Xvfb process. So I am trying this:

    String line;
    try {
      Process p = Runtime.getRuntime().exec("ps -ef | grep Xvfb | grep -v grep");
      BufferedReader input = new BufferedReader(new InputStreamReader(p.getInputStream()));
      while ((line = input.readLine()) != null)
      {
        System.out.println(line);
      }
    } catch (Exception err) {
      System.out.println(err);
    }

The bizarre thing is that if I use "ps -ef", I get a huge list of processes dumped to my console when I run my app. But if I use | grep to narrow the list of processes returned, I get zero results. input.readLine() gets null every time.

I have also tried:

    ps -ef | grep Xvfb | grep -v grep | awk {'print $2'}

To just grab the process id. Also, no luck.

Has anyone else experienced this or know what I'm doing wrong?

解决方案

You're trying to use the "|" which is a pipe function that is particular to the shell, therefore you cannot do it in the java process. You could just try getting the process ID by using pidof Xvfb.

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