Util class:
--------------------------------UTIL CLASS START-------------------------------------
 public static void runShellCommandAsync(CommandSender sender, String command)
    {
        new BukkitRunnable()
        {
            @Override
            public void run()
            {
                try {
              runShellCommand(sender, command);
                }
                catch(IOException ex) {
                    LF_Log.severe(ex);
                    sender.sendMessage("Invalid command");
                }
                catch(InterruptedException ex) {
                    sender.sendMessage("Error, see logs for more details");
                    LF_Log.severe(ex);
                }
            }
        }.runTaskAsynchronously(LFUtils.plugin);

    }

    public static void runShellCommand(CommandSender sender, String command) throws InterruptedException, IOException
    {
        Process proc = Runtime.getRuntime().exec(command);

        // Read the output
        BufferedReader reader
                = new BufferedReader(new InputStreamReader(proc.getInputStream()));

        String line = "";
        while ((line = reader.readLine()) != null)
        {
            sender.sendMessage(line);
        }

        proc.waitFor();
    }

-------------- UTIL CLASS OVER ----------------------------

Command:
----------------------- COMMAND START -------------------------

        if(args.length == 0) {
            return false;
        }
        runShellCommandAsync(sender, StringUtils.join(args, " "));
        return true;

----------------------COMMAND END-----------------