Java程序未显示控制台的输出

Question

我已经看了几个可以做到这一点的例子，就核心机制而言，我和其他人之间没有任何区别。 这是我的代码：

public class Console 
{
    public static void main(String[] args) throws IOException, InterruptedException{
        Runtime rt = Runtime.getRuntime();
        Process ps;
        System.out.println("Gathering available network data...");    

        String cmd[] = {"ifconfig","|","grep","'inet addr:'"};
        ps = rt.exec(cmd);  
        getOutput(cmd,ps);
    }
    public static String getOutput(String[] c, Process p) throws IOException, InterruptedException
    {
        Process ps = p;
        String output="";
        BufferedReader readerStd = new BufferedReader(new InputStreamReader(ps.getInputStream()));  
        BufferedReader readerErr = new BufferedReader(new InputStreamReader(ps.getInputStream()));  

        String line = null;
        System.out.println("Result:");  
        while ((line = readerStd.readLine()) != null) {  
            System.out.println(line);  
            output+=line+"\n";
        }  

        if((line = readerErr.readLine()) != null)
        {
            System.out.println("------ Std Err -------");
            System.out.println(line);
            while ((line = readerErr.readLine()) != null) 
            {  
                System.out.println(line);  
            }
        }
        return output;
    }   
}

预期的输出是：

Gathering available network data...
Result:
          inet addr:10.40.2.234  Bcast:10.40.2.255  Mask:255.255.255.0
          inet addr:127.0.0.1  Mask:255.0.0.0

实际输出为：

Gathering available network data...
Result:

我究竟做错了什么？

Answer 1

管道操作员| 被解释为外壳，因此不构成命令本身的一部分。 另外，该命令需要出现在单个标记中，以防止对grep段进行单独评估：

String cmd[] = { "bash", "-c", "ifconfig |grep 'inet addr:'" };