Java program not displaying output from console

Question

I've looked at several examples that are supposed to do this, and I don't see any difference between mine and others as far as core mechanics. Here is my code:

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;
    }   
}

The expected output is:

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

The actual output is:

Gathering available network data...
Result:

What am I doing wrong?

Answer 1

The pipe operator | is interpreted the shell so does not form part of the command itself. In addition the command needs to appear in a single token to prevent the grep segment being evaluated separately:

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