Develop Reference

Execute logcat with tag on Android returns empy

I have an Activity which every second write a counter to the logcat:
Runnable rLog = new Runnable() {
#Override
public void run() {
i++;
Log.d("bbb", "i= " + i);
handler.postDelayed(this, 1000);
}
};
In addition - I have a service which read from "logcat -s bbb" and log it:
Runnable rGetLog = new Runnable() {
#Override
public void run() {
Runtime rt = Runtime.getRuntime();
Process process = null;
try {
process = rt.exec("logcat -s bbb");
} catch (IOException e1) {
e1.printStackTrace();
}
BufferedReader bufferedReader =
new BufferedReader(new InputStreamReader(process.getInputStream()));
try {
while ((line = bufferedReader.readLine()) != null)
{
Log.d("aaa", "get line = " + line);
}
} catch (IOException e) {
e.printStackTrace();
}
}
};
This code works well. The problem starts when I change the tag "bbb" to a real tag such as "AndroidRuntime" or another tag... I got an empty response from logcat
(if I run at the same time "logcat -s AndroidRuntime" from adb I got lots of lines...)
Who knows what the problem is? what can be different?
Thanks!

From Android Jelly Bean, applications cannot read log entries from other applications, unless your device is rooted and you read the logs as superuser.
try using sudo to get permissions:
process = rt.exec("su && logcat -s YOUR_TAG");

How to uninstall android system app programmatically?

I can get a list of installed apps (both user and system apps). I am also able to uninstall user apps, however, not able to uninstall system apps.
Is there any way to uninstall system app?
If the phone is already rooted, will the following code work?
Intent intent = new Intent(Intent.ACTION_DELETE);
intent.setData(Uri.parse("package:"+appPackageName.getText().toString()));
context.startActivity(intent);

you can execute root commands with:
runCommand("su");
runCommand("rm /data/system/application.package.apk");
runCommand("rm /data/data/application.package");
//when this doesn´t work try
runCommand("rm -r /data/system/application.package.apk");
runCommand("rm -r /data/data/application.package");
public static void runCommand(String command){
try {
Process chmod = Runtime.getRuntime().exec(command);
BufferedReader reader = new BufferedReader(
new InputStreamReader(chmod.getInputStream()));
int read;
char[] buffer = new char[4096];
StringBuffer output = new StringBuffer();
while ((read = reader.read(buffer)) > 0) {
output.append(buffer, 0, read);
}
reader.close();
chmod.waitFor();
outputString = output.toString();
} catch (IOException e) {
throw new RuntimeException(e);
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
}
There is also a nice library: https://github.com/Free-Software-for-Android/RootCommands

You need to have root access in order to remove system or vendor apps.
$ su
# rm /data/system/application.package.apk
# rm /data/data/application.package

Try this on Rooted Device...it works
Process reboot = Runtime.getRuntime().exec("su");
DataOutputStream os = new DataOutputStream(reboot.getOutputStream());
os.writeBytes("pm uninstall co.example.demo\n");
os.flush();
os.writeBytes("exit\n");
os.flush();
reboot.waitFor();

Clear android application user data

Using adb shell we can clear application data.
adb shell pm clear com.android.browser
But when executing that command from the application
String deleteCmd = "pm clear com.android.browser";
Runtime runtime = Runtime.getRuntime();
try {
runtime.exec(deleteCmd);
} catch (IOException e) {
e.printStackTrace();
}
Issue:
It doesn't clear the user data nor give any exception though I have given the following permission.
<uses-permission android:name="android.permission.CLEAR_APP_USER_DATA"/>
Question:
How to clear another app application data using adb shell?

This command worked for me:
adb shell pm clear packageName

Afaik the Browser application data is NOT clearable for other apps, since it is store in private_mode. So executing this command could probalby only work on rooted devices. Otherwise you should try another approach.

The command pm clear com.android.browser requires root permission.
So, run su first.
Here is the sample code:
private static final String CHARSET_NAME = "UTF-8";
String cmd = "pm clear com.android.browser";
ProcessBuilder pb = new ProcessBuilder().redirectErrorStream(true).command("su");
Process p = pb.start();
// We must handle the result stream in another Thread first
StreamReader stdoutReader = new StreamReader(p.getInputStream(), CHARSET_NAME);
stdoutReader.start();
out = p.getOutputStream();
out.write((cmd + "\n").getBytes(CHARSET_NAME));
out.write(("exit" + "\n").getBytes(CHARSET_NAME));
out.flush();
p.waitFor();
String result = stdoutReader.getResult();
The class StreamReader:
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.concurrent.CountDownLatch;
class StreamReader extends Thread {
private InputStream is;
private StringBuffer mBuffer;
private String mCharset;
private CountDownLatch mCountDownLatch;
StreamReader(InputStream is, String charset) {
this.is = is;
mCharset = charset;
mBuffer = new StringBuffer("");
mCountDownLatch = new CountDownLatch(1);
}
String getResult() {
try {
mCountDownLatch.await();
} catch (InterruptedException e) {
e.printStackTrace();
}
return mBuffer.toString();
}
#Override
public void run() {
InputStreamReader isr = null;
try {
isr = new InputStreamReader(is, mCharset);
int c = -1;
while ((c = isr.read()) != -1) {
mBuffer.append((char) c);
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (isr != null)
isr.close();
} catch (IOException e) {
e.printStackTrace();
}
mCountDownLatch.countDown();
}
}
}

To clear Application Data Please Try this way.
public void clearApplicationData() {
File cache = getCacheDir();
File appDir = new File(cache.getParent());
if (appDir.exists()) {
String[] children = appDir.list();
for (String s : children) {
if (!s.equals("lib")) {
deleteDir(new File(appDir, s));Log.i("TAG", "**************** File /data/data/APP_PACKAGE/" + s + " DELETED *******************");
}
}
}
}
public static boolean deleteDir(File dir) {
if (dir != null && dir.isDirectory()) {
String[] children = dir.list();
for (int i = 0; i < children.length; i++) {
boolean success = deleteDir(new File(dir, children[i]));
if (!success) {
return false;
}
}
}
return dir.delete();
}

To reset/clear application data on Android, you need to check available packages installed on your Android device-
Go to adb shell by running adb shell on terminal
Check available packages by running pm list packages
If package name is available which you want to reset, then run pm clear packageName by replacing packageName with the package name which you want to reset, and same is showing on pm list packages result.
If package name isn't showing, and you will try to reset, you will get Failed status.

On mac you can clear the app data using this command
adb shell pm clear com.example.healitia

To clear the cache for all installed apps:
use adb shell to get into device shell ..
run the following command : cmd package list packages|cut -d":" -f2|while read package ;do pm clear $package;done

// To delete all the folders and files within folders recursively
File sdDir = new File(sdPath);
if(sdDir.exists())
deleteRecursive(sdDir);
// Delete any folder on a device if exists
void deleteRecursive(File fileOrDirectory) {
if (fileOrDirectory.isDirectory())
for (File child : fileOrDirectory.listFiles())
deleteRecursive(child);
fileOrDirectory.delete();
}

How to get error message of a failed shell command on android

On a rooted android device, I tried to run a cat command that read kernel log, as follow:
Process p = Runtime.getRuntime().exec("su");
p = Runtime.getRuntime().exec("/system/bin/cat /proc/kmsg");
The su command was successfully executed but not the cat.
I tried to read the output of the command using getInputStream() but nothing was there, as follow:
BufferedReader in = new BufferedReader(new InputStreamReader(p.getInputStream()));
while ((read = err.read(buffer)) > 0)
{ //read error to buffer
catOutput.append(buffer, 0, read);
}
in.close();
I used the same code with ls command instead of displaying the kernel log, it worked just fine and show me the result.
I wonder if what error I am getting and wantted to see the error message on the shell when executing the cat command. Tried the p.getErrorStream() but it doesn't give me any result.
Could any one help me with this ? Thanks.

Here's a comprehensive example on how to do this - note that I got the idea from this answer:
public void catKmsg() {
Runtime runtime = Runtime.getRuntime();
Process proc = null;
OutputStreamWriter osw = null;
StringBuilder sbstdOut = new StringBuilder();
StringBuilder sbstdErr = new StringBuilder();
String command="/system/bin/cat /proc/kmsg";
try { // Run Script
proc = runtime.exec("su");
osw = new OutputStreamWriter(proc.getOutputStream());
osw.write(command);
osw.flush();
osw.close();
} catch (IOException ex) {
ex.printStackTrace();
} finally {
if (osw != null) {
try {
osw.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
try {
if (proc != null) {
proc.waitFor();
}
} catch (InterruptedException e) {
e.printStackTrace();
}
sbstdOut.append(ReadBufferedReader(new InputStreamReader
(proc.getInputStream())));
sbstdErr.append(ReadBufferedReader(new InputStreamReader
(proc.getErrorStream())));
if (proc.exitValue() != 0) {
}
}

I finally found the solution for the problem by using RootTools library.
Recently released (few months after my question was asked), RootTools provides a easy-to-use tool set that helps running commands that required root privilege. I created a wrapper to check if root access is available before executing shell command:
void testRootToolsCommand(String command){
if (RootTools.isRootAvailable())
toastMessage("Root is available !!!");
else {
toastMessage("NO ROOT !!! ");
return;
}
int timeOut = 1000;
try {
List<String> output = RootTools.sendShell(command,timeOut);
toastMessage("OUTPUT of the command \n" + output.toString());
} catch (RootToolsException re) {
toastMessage("Funny thing happened with RootTools!!! ");
} catch (TimeoutException te)
{
toastMessage("Timeout exception - Increase timeout !!! !!! ");
}
catch (Exception e) {
toastMessage(e.getMessage().toString());
}
}
An example of a function call is:
testRootToolsCommand("cat /proc/kmsg > /sdcard/jun11_4h51.txt");
Note: The Tool also support running multiple commands at once.

Run shell commands from android program

This question has been asked here before but the solutions provided are not working..I am trying to display the contents of /data/dalvik-cache folder. I know that to do this we need to become su. I even did that but still i am unable to execute a shell command..
package org.linuxconfidg.Example2;
import android.app.Activity;
import android.widget.*;
import android.os.Bundle;
import java.io.*;
public class Example2Activity extends Activity {
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
String lsreturn=myFunLs();
TextView tv=new TextView(this);
tv.setText("Hello Sindhu !! Try to get it \n"+lsreturn);
setContentView(tv);
}
public String myFunLs()
{
try {
// Executes the command.
Process process;
process = Runtime.getRuntime().exec("/system/bin/su");
process = Runtime.getRuntime().exec("/system/bin/ls /data/dalvik-cache > /data/local");
pr
BufferedReader reader = new BufferedReader(
new InputStreamReader(process.getInputStream()));
int read;
char[] buffer = new char[4096];
StringBuffer output = new StringBuffer();
while ((read = reader.read(buffer)) > 0) {
output.append(buffer, 0, read);
}
reader.close();
// Waits for the command to finish.
process.waitFor();
return output.toString();
} catch (IOException e) {
throw new RuntimeException(e);
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
}
}
Can anyone please help me out in finding out how to run linux commands in android application. I am testing this app in my emulator which is defaultly rooted

You can't simply run 'su' on the emulator, there's no root access by default. You'll need to install the 'su' program as well as the SuperUser.apk, and you'll have to do this each time you start the emulator unless using snapshots.
More information and links to the files you need can be found here on SO as well as this blog post by Russell Davis

I think the problem comes from the fact that you are using TWO different process instances.
You have to be on the su process to carry on sending commands:
You can check the question "Read command output inside su process"
for an answer.
Then I tried & managed to make working code (I'm sure it works!)
public void runAsRoot(String[] cmds) throws Exception {
Process p = Runtime.getRuntime().exec("su");
DataOutputStream os = new DataOutputStream(p.getOutputStream());
InputStream is = p.getInputStream();
for (String tmpCmd : cmds) {
os.writeBytes(tmpCmd+"\n");
int readed = 0;
byte[] buff = new byte[4096];
// if cmd requires an output
// due to the blocking behaviour of read(...)
boolean cmdRequiresAnOutput = true;
if (cmdRequiresAnOutput) {
while( is.available() <= 0) {
try { Thread.sleep(200); } catch(Exception ex) {}
}
while( is.available() > 0) {
readed = is.read(buff);
if ( readed <= 0 ) break;
String seg = new String(buff,0,readed);
console.println("#> "+seg);
}
}
}
os.writeBytes("exit\n");
os.flush();
}

In the below example, I try to execute "/system/bin/screencap" to capture android screen.
via adb:
> adb shell
# /system/bin/screencap -p /sdcard/myscreenshot.png
via Android app:
sh = Runtime.getRuntime().exec("su", null,null);
OutputStream os = sh.getOutputStream();
os.write(("/system/bin/screencap -p " + path).getBytes("ASCII"));
os.flush();
os.close();
sh.waitFor();
Hope this helps.