The first thing you should do is to log the stderr stream that is available for your process as well. This will give you information about what is wrong with your command.

Your command is not correctly processed as it is seen as one command. The reason is explained in this answer.

The solution is to use a String[] as an argument of exec and explicitly execute the command with the shell. I wrote some code that executes your command, but it is in Java on an unrooted device. Still, it generates output and grep works.

String[] arrayCommand = {"sh", "-c","dumpsys telephony.registry | grep \"permission\""};
            
Runtime r = Runtime.getRuntime();
Process process = r.exec(arrayCommand);

String stdoutString = convertInputStreamToString(process.getInputStream());
String stderrString = convertInputStreamToString(process.getErrorStream());

First, you should wrap calls to exec in a try-catch-clause to catch IOExceptions.

Second, use exec(java.lang.String[]) to execute a command with parameters. For example, similar to

Runtime.getRuntime().exec(new String[]{ "shell", "/system/bin/chmod", "0777", sdCard.getAbsolutePath() + "/" + nativeFile });

@Adi Tiwari, I've found the cause. Runtime.getRuntime.exec() doesn't execute a shell command directly, it executes an executable with arguments. "echo" is a builtin shell command. It is actually a part of the argument of the executable sh with the option -c. Commands like ls are actual executables. You can use type echo and type ls command in adb shell to see the difference.
So final code is:

String[] cmdline = { "sh", "-c", "echo $BOOTCLASSPATH" }; 
Runtime.getRuntime().exec(cmdline);

If you are using service to check every 5 seconds then you must return START_NOT_STICKY from override method onStartCommand() if you want to prevent it start service automatically when it crashes.

Android java.lang.Process implementation is java.lang.ProcessManager$ProcessImpl and it has field private final int pid;. It can be get from Reflection:

public static int getPid(Process p) {
    int pid = -1;

    try {
        Field f = p.getClass().getDeclaredField("pid");
        f.setAccessible(true);
        pid = f.getInt(p);
        f.setAccessible(false);
    } catch (Throwable e) {
        pid = -1;
    }
    return pid;
}

Another way - use toString:

    public String toString() {
        return "Process[pid=" + pid + "]";
    }

You can parse output and get pid without Reflection.

So full method:

public static int getPid(Process p) {
    int pid = -1;

    try {
        Field f = p.getClass().getDeclaredField("pid");
        f.setAccessible(true);
        pid = f.getInt(p);
        f.setAccessible(false);
    } catch (Throwable ignored) {
        try {
            Matcher m = Pattern.compile("pid=(\\d+)").matcher(p.toString());
            pid = m.find() ? Integer.parseInt(m.group(1)) : -1;
        } catch (Throwable ignored2) {
            pid = -1;
        }
    }
    return pid;
}

You probably still need to have the WRITE_EXTERNAL_STORAGE permission, in case you do not have that.

Your bigger problem is that cp is not in any sort of PATH. In fact, I do not see the cp command anywhere on the Android 2.2 emulator, though I have not done an exhaustive search.

The way a savvy programmer would solve this is using Java, since that eliminates your dependency on undocumented/unsupported command-line binaries.

Redirection (>) is not the OS feature. This is a feature of shell. To make it working from java you have to run something like the following:

/bin/sh yourcommand > yourfile

i.e. in your case:

/bin/sh cat /sdcard/file1.mpg /sdcard/file2.mpg > /sdcard/out.mpg

BUT could you please explain me why are you doeing this? Do you understand that this command is exact equivalent of cp /sdcard/file1.mpg /sdcard/file2.mpg /sdcard/out.mpg that can be coded in pure java without running any command line? Unless you have special reasons go on it! Write pure java code when it is possible. It is easier to debug, support and maintain.

The "su -c COMMAND" syntax is not really supported. For better portability, use something like this:

p = Runtime.getRuntime().exec("su");
stream = p.getOutputStream();
stream.write("busybox ifconfig wlan0 add xxxxxxxxxxxx");

The write() command doesn't exists as-is, but I'm sure you'll find how to write your stream to it, maybe encapsulating the output stream in a BufferedOutputWriter or so.

why not use p.getInputStream().read() to read what you need to send while using out.write() to send data accordingly.

here is an example taken from: http://www.rgagnon.com/javadetails/java-0014.html

String line;
OutputStream stdin = null;
InputStream stderr = null;
InputStream stdout = null;

  // launch EXE and grab stdin/stdout and stderr
  Process process = Runtime.getRuntime ().exec ("/folder/exec.exe");
  stdin = process.getOutputStream ();
  stderr = process.getErrorStream ();
  stdout = process.getInputStream ();

  // "write" the parms into stdin
  line = "param1" + "\n";
  stdin.write(line.getBytes() );
  stdin.flush();

  line = "param2" + "\n";
  stdin.write(line.getBytes() );
  stdin.flush();

  line = "param3" + "\n";
  stdin.write(line.getBytes() );
  stdin.flush();

  stdin.close();

  // clean up if any output in stdout
  BufferedReader brCleanUp =
    new BufferedReader (new InputStreamReader (stdout));
  while ((line = brCleanUp.readLine ()) != null) {
    //System.out.println ("[Stdout] " + line);
  }
  brCleanUp.close();

  // clean up if any output in stderr
  brCleanUp =
    new BufferedReader (new InputStreamReader (stderr));
  while ((line = brCleanUp.readLine ()) != null) {
    //System.out.println ("[Stderr] " + line);
  }
  brCleanUp.close();

You can execute ls with provided path for which folders should be listed

Runtime.getRuntime().exec(new String[] { "ls", "\\tmp"});