Question

I would like a help from u all .I am using java and i want to execute the a command that is use to get the channels details in asterisk. the system is linux based.
I want to execute command “core show channels” at the same time want to grep channels also

Following is the command and the output when fire normally in console.

   asterisk -vvvvvrx 'core show channels' | grep channels

and the output is
2 active channels

I am trying to use following code in java

import java.io.IOException;
import java.util.*;
import java.io.BufferedReader;
import java.io.InputStreamReader;
public class ProcessBuilderExample
{
  public static void main(String[] args) 
  throws IOException, InterruptedException
  {
  String[] commands = new String[]{"asterisk","-rx","core show channels","| grep 'channels'"};
 Process p = Runtime.getRuntime().exec(commands);
    p.waitFor();
   BufferedReader br = new BufferedReader(new InputStreamReader(p.getInputStream()));
   String line = "";
while((line = br.readLine()) != null) {
      System.out.println(line);
}
    System.out.println("hello");
  }
}

but it is not showing me the correct output pls help me to solve this problem

Answer 1

Try to change

String[] commands = new String[]{"asterisk","-rx","core show channels","| grep 'channels'"};

to:

String[] commands = new String[]{"/bin/sh", "-c", "asterisk -rx 'core show channels' | grep 'channels'"};

Reason:

Your vertical bar will be interpreted as “\|”(i.e. literally “|” instead of a pipe”), if we instead invoke a shell command(/bin/sh) and put the whole command as its argument, vertical bar will be correctly interpreted.