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Read logs from code programmatically and matching with a string in android app

How can we read logs(verbose,debug etc) programmatically from android class and then search for a string or matching with a provided string in android.
Sometimes we need to handle some system or kernel layer related event. But as we have limited access of those code we can't handle them. We can see the logcat via adb and also see some log comes from kernel/framework layer.
Now the question is, How we can override or handling some event in our app based on those logs?

Here is a solution to this from any android app:
We need to make a class with some code like below:
public class LogsUtil {
private static final String processId = Integer.toString(android.os.Process
.myPid());
public static StringBuilder readLogs() {
StringBuilder logBuilder = new StringBuilder();
try {
String[] command = new String[] { "logcat", "-d", "threadtime" };
Process process = Runtime.getRuntime().exec(command);
BufferedReader bufferedReader = new BufferedReader(
new InputStreamReader(process.getInputStream()));
String line;
while ((line = bufferedReader.readLine()) != null) {
if (line.contains(processId)) {
logBuilder.append(line);
//Code here
}
}
} catch (IOException e) {
}
return logBuilder;
}
}
Then need to write below code in our activity from where we need to check the logs string:
//read the logs
StringBuilder logs = LogsUtil.readLogs();
if(logs.toString().contains("your_text"))
//your code
else //your code

To use sudo feature, what should I wrote in the my application?

To use sudo feature, what should I write in the my application? Should I write something? If yes, can you tell me how I can write sudo application? Do I need to change manifest.xml, or add some Java code?

Assuming the device is rooted and your app has been granted superuser permissions, you can use the following method to run commands as root:
public static void runAsRoot(String[] cmds){
Process p;
try {
p = Runtime.getRuntime().exec("su");
DataOutputStream os = new DataOutputStream(p.getOutputStream());
BufferedReader bf = new BufferedReader(new InputStreamReader(p.getInputStream()));
for (String tmpCmd : cmds) {
os.writeBytes(tmpCmd+"\n");
String test;
while((test = bf.readLine()) != null)
{
Log.i(TAG, test);
}
}
//os.writeBytes("exit\n");
os.flush();
} catch (IOException e) {
e.printStackTrace();
}
}
Just pass it a list of commands in a String array.

iptables Rules show in textView in android;

i want to show the rules i've created in a textView, using this code;
..................................
public void show(View btn) throws IOException{
Show(tv);
}
public final void Show(TextView tv) throws IOException{
Process Q =Runtime.getRuntime().exec("su -c iptables -L INPUT 1 -n -v --line-numbers ");
String pingResult="";
BufferedReader in = new BufferedReader(new
InputStreamReader(Q.getInputStream()));
String inputLine;
while ((inputLine = in.readLine()) != null) {
tv.setText(pingResult+="\n"+inputLine+"\n");
}
in.close();
}
}
the problem is that it tells me superuser permission granted, but the table doesn't appear in the TextView, even though i've used BufferReader ..... help ?

With this code portion Im doing the same you need but listing a directory and reading the input. Try using this code changing the getRuntime().exec Command.
private String[] GetAppFiles() throws IOException
{
int BUFF_LEN =2048;
Process p = Runtime.getRuntime().exec(new String[]{"su", "-c", "system/bin/sh"});
DataOutputStream stdin = new DataOutputStream(p.getOutputStream());
//from here all commands are executed with su permissions
stdin.writeBytes("ls " + CurrentApkPath + "\n"); // \n executes the command
InputStream stdout = p.getInputStream();
byte[] buffer = new byte[BUFF_LEN];
int read;
String out = new String();
//read method will wait forever if there is nothing in the stream
//so we need to read it in another way than while((read=stdout.read(buffer))>0)
while(true){
read = stdout.read(buffer);
out += new String(buffer, 0, read);
if(read<BUFF_LEN){
//we have read everything
break;
}
}
I hope it helps you.

why process give null inputstream in test runner class?

In my android test project, I simply read the logcat using adb command
like,
public StringBuilder log=new StringBuilder();
public String line="";
public String temp="";
public void testSolo() throws Exception {
String baseCommand = "logcat -v time";
baseCommand += " ActivityManager:I "; // Info for my app
baseCommand += " *:S "; // Silence others
try {
Process logReaderProcess = Runtime.getRuntime().exec(baseCommand);
BufferedReader bufferedReader = new BufferedReader(
new InputStreamReader(logReaderProcess.getInputStream()));
while ((line =bufferedReader.readLine()) != null) {
log.append(line); // here readLine() returns null
}
}
catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
}
but, here in string line I always get null value,
while the same thing always run in the android activity's onCreate() .
I don't understand why this happen?
Same thing runs in activity class and not in the android test project.
I also add use -permission for READ_LOGS and WRITE_EXTERNAL_STORAGE in test project's
manifest.xml file.
Is there anybody knows how it works or what happens?
Thanks in advance.

Try to add
<uses-permission android:name="android.permission.READ_LOGS" />
to your manifest.

String []baseCommand = new String[]{"logcat", "-v","time"};
Process logReaderProcess = Runtime.getRuntime().exec(baseCommand);
try this out

Reading Logcat within the app returns null

I read the other posts and can't figure out the "trick".
I looked at Log Collector but can't use a separate APK. I'm basically using the same approach and I consistently get nothing back on the processes inputstream.
I have READ_LOGS in the manifest.
From within my default activity, I'm able to get the log, but if I move the logic to another activity or utilize an asynctask, no output is returned.
this code is from my default activity... inline, i dump it to the log
try {
Process process = Runtime.getRuntime().exec("logcat -d");
BufferedReader bufferedReader = new BufferedReader(
new InputStreamReader(process.getInputStream()));
StringBuilder log=new StringBuilder();
String line;
while ((line = bufferedReader.readLine()) != null) {
log.append(line);
}
Log.d(LOGTAG, "Logcat: " +log.toString());
} catch (IOException e) {}
if i wrap it in an asynctask or just inline it in another activity, it returns nothing
ArrayList<String> commandLine = new ArrayList<String>();
//terminate on completion and suppress everything except the filter
commandLine.add("logcat -d -s");
...
//replace asynctask with inline (could not get log in asynctask)
showProgressDialog(getString(R.string.acquiring_log_progress_dialog_message));
final StringBuilder log = new StringBuilder();
BufferedReader bufferedReader = null;
try{
Process process = Runtime.getRuntime().exec(commandLine.toArray(new String[0]));
bufferedReader = new BufferedReader(new InputStreamReader(process.getInputStream()));
String line;
while ((line = bufferedReader.readLine()) != null){
log.append(line);
log.append(MangoApp.LINE_SEPARATOR);
}
sendIntent.putExtra(Intent.EXTRA_TEXT, log.toString());
startActivity(Intent.createChooser(sendIntent, getString(R.string.chooser_title)));
dismissProgressDialog();
dismissMainDialog();
finish();
}
catch (IOException e){
dismissProgressDialog();
showErrorDialog(getString(R.string.failed_to_get_log_message));
Log.e(LOGTAG, "Log collection failed: ", e);//$NON-NLS-1$
} finally {
if (bufferedReader != null) {
try {
bufferedReader.close();
} catch (IOException ignore) {}
}
}
Can anyone spot the diff or explain the magic? I'm pretty sure the commandline is right in the second version so scratching my head. I'm using 2.1 SDK 7 on the emulator.
Thanks

Hope this will be helpful, you don't have to create file by your self just execute the below command, to get the error info.
Runtime.getRuntime().exec("logcat -v time -r 100 -f /sdcard/log.txt *:E");
Logcat parameters options:
-r <size in kilobytes> -> for specifying the size of file
-f <filename> -> file to which you want to write the logs.

Can you try it without the ArrayList. Just pass the command String
I have implemented it in the following way (without the ArrayList). It works for me.
String baseCommand = "logcat -v time";
baseCommand += " MyApp:I "; // Info for my app
baseCommand += " *:S "; // Silence others
ServicesController.logReaderProcess = Runtime.getRuntime().exec(baseCommand);