How to constanly monitor LogCat file?

Question

I need to somehow monitor the LogCat log, meaning that while my service is running I need to read the LogCat for new entries. At this moment I know only how to retrieve once the Log:

Process mLogcatProc = null;
    BufferedReader reader = null;
    try
    {
            mLogcatProc = Runtime.getRuntime().exec(new String[]
                   {"logcat", "-d", "ActivityManager:I *:S" });        

            reader = new BufferedReader(new InputStreamReader
    (mLogcatProc.getInputStream()));

            String line;
            final StringBuilder log = new StringBuilder();
            String separator = System.getProperty("line.separator"); 

            while ((line = reader.readLine()) != null)
            {
                    log.append(line);
                    log.append(separator);
            }

If I remove the -d option it will not exit but also it will not either work. So how can I modify the bellow code in order to continuously read new entries from LogCat?

May I ask why you want to do this? It sounds like a generally bad idea. — torkildr, Jan 11 '11 at 18:42
Because it seems to be the only way to know when an activity starts. For what ? For an application protection app. Like App Protector.. and if you look on the permissions it needs reading system logs... — Alex, Jan 11 '11 at 18:55
Hey Alex , did you find the answer to this. I am looking to this as well — Anuj Tenani, Mar 27 '11 at 15:55

score 6 · Answer 1 · edited Dec 16 '14 at 22:13

6

This is how I did it, using Jiahao Liu's suggestion:

ReadThread thread;

public void startRecordingLogs()
{
  if(thread == null || !thread.isAlive())
  {
    ReadThread thread = new ReadThread();
    thread.start();
  }
}

public String stopRecordingLogs()
{
  String results = thread.stopLogging();
  return results;
}

private class ReadThread extends Thread{

  String results;
  Process process;
  Object lockObject = new Object();

  public void run(){
    synchronized(lockObject)
    {
      process = Runtime.getRuntime().exec("logcat -v time");        

      reader = new BufferedReader(new InputStreamReader (process.getInputStream()));

      String line;
      final StringBuilder log = new StringBuilder();
      String separator = System.getProperty("line.separator"); 

      while ((line = reader.readLine()) != null)
      {
        log.append(line);
        log.append(separator);
      }
    }

    results = log.toString();
  }

  public String stopLogging()
  {
    process.destroy();
    synchronized(lockObject)
    {
      return results;
    }
  }
}

edited Dec 16 '14 at 22:13

James

5
1
4

answered Aug 09 '12 at 04:51

you786

3,735
4
42
67

where is "results" defined? – gonzobrains May 07 '13 at 21:04
@gonzobrains Right under where the ReadThread class is defined. – you786 May 07 '13 at 21:05
Yes, but unless I define another "results" outside of the class then results isn't defined for stopRecordingLogs(). – gonzobrains May 07 '13 at 21:26
Did this code work for logging all logcat activity or only for your app's particular activity? I need to log all activity. Actually, I don't really want to just log; I want to scan and raise events if certain items are found in the logcat activity. – gonzobrains May 07 '13 at 21:39
For all logcat activity, and I've used it in the same manner you've described. – you786 May 07 '13 at 21:40
Can you post your code for that? I need to scan for particular entries and then post an event of some sort for another object to handle. Do I need to create a new SO question for you to answer for that? – gonzobrains May 07 '13 at 21:51
done. http://stackoverflow.com/questions/16429349/how-do-you-scan-logcat-output-and-post-event-based-on-found-text – gonzobrains May 07 '13 at 22:07
let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/29565/discussion-between-gonzobrains-and-you786) – gonzobrains May 07 '13 at 22:43
I fixed my null issue. I needed to add permissions to AndroidManifest.xml. – gonzobrains May 08 '13 at 01:28
It's been awhile, but I think I used android.permission.READ_LOGS. – gonzobrains Feb 08 '16 at 15:12

score 2 · Answer 2 · answered May 01 '11 at 19:32

2

You can create a new thread to running the logcat(without the option -d) in the background.

Note: Use the buffer events instead of the process ActivityManager, it is more accurate. "logcat -b events"

answered May 01 '11 at 19:32

Jiahao Liu

21
2

How to constanly monitor LogCat file?

2 Answers2

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