Read output from shell command with pipes on Android

Question

I'm trying to execute a shell command in an android app (Java) and read the output. I can read the output of most commands but I am unable to get anything when I use a pipe in the command. The device is rooted.

I've found this but it doesn't want to work on Android. I've tried output redirects, eg "2>&1" at the end of the command but no luck.

Thanks in advance!

Working Command

pm list packages

Not Working Command

pm list packages | grep com.myapp

Code:

public String executeCommand(String command) {
    String output = "";

        InputStream inputStream = Runtime.getRuntime().exec(command).getInputStream();

        while( inputStream.available() <= 0) 
            try { Thread.sleep(500); } catch(Exception ex) {}

        java.util.Scanner s = new java.util.Scanner(inputStream);
        while(s.hasNext())
            output += s.nextLine() + "\n";

            return output; 
}

Try and catch blocks omitted for brevity

Answer 1

My bet is that grep is not installed on your device. You can check it by starting up an ADB shell and typing in grep and you should probably see

> adb shell
$ grep
grep: not found

I suggest you filter the results on your own in Java as not all devices have grep preinstalled.

Answer 2

It's been over two years now, but one can try this:

Instead:

Runtime.getRuntime().exec(command);

call:

String[] shell = {"sh", "-c", command};
Runtime.getRuntime().exec(shell);