How can I get logcat on my device to show logs from all processes

Question

I'm trying to write an app that reads all logs on my device. I've got a client/service architecture, and I see log messages from both the client and service processes but I don't see any messages from any other applications on the phone (I do see other messages using the desktop logcat).

Do I need root?

Code Snippets

Manifest

<uses-permission android:name="android.permission.READ_LOGS" />

Log Reader

Runtime.getRuntime().exec("logcat -c").waitFor();

Process process = Runtime.getRuntime().exec("logcat -v long *:*");
BufferedReader reader = 
    new BufferedReader(new InputStreamReader(process.getInputStream()));
while (true) {
    String nextLine = reader.readLine();
    if (!nextLine.contains("LogWatcher-D")) {
        Log.w("LogWatcher-D", "See: " + nextLine);
    }

    // Process line
}

Answer 1

On Android 4.1+, you can only access log messages logged by your process, unless you hold the READ_LOGS permission. That permission requires either that your app be signed by the same signing key that signed the device's firmware, or that your app is installed on the system partition.