Develop Reference

on android how to find the original file if got a hard link

in the app when receiving an intent which was created from other app and has a file path, it can access the file's content using the file path.
the question is if that path (call it as 'link-path') is a 'hard link' to the original file, is it possible to find the original file through this 'link-path'?
Searched and find some post like:
https://unix.stackexchange.com/questions/122333/how-to-tell-which-file-is-original-if-hard-link-is-created
they show some unix shell command. Not sure if there is some android file system support for this, anyone having suggestion?

You can use this code I made, based on this post. It will return the target path of any path. If path is not a symbolic link, it will return itself. If path doesn't exist it returns null.
public static String findLinkTarget(String path) {
try {
Process findTarget = Runtime.getRuntime().exec("readlink -f " + path);
BufferedReader br = new BufferedReader(new InputStreamReader(findTarget.getInputStream()));
return br.readLine();
} catch (IOException e) {
Log.w(TAG, "Couldn't find target file for link: " + path, e);
}
}
The code wasn't tested, but I tested the command on Termux and it worked.
EDIT: Try calling getCanonicalPath() on your file, I think it resolves the symlink.

find a way by comparing the inode, in api >21 android has Os to get it, otherwise using the command "ls -i" to get the inode. One issue though, tested on api<=18 the "ls -i" does not return any thing (tested on emulator), in that case maybe fallback to compare the file's size and timestamp.
static String getFileInode(File file) {
String inode = "-1";
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
StructStat st = null;
try {
ParcelFileDescriptor pfd = ParcelFileDescriptor.open(file,
ParcelFileDescriptor.parseMode("r"));
st = Os.fstat (pfd.getFileDescriptor());
if (st != null) {
inode = ""+st.st_ino;
}
} catch (Exception e) {
Log.e(TAG, "fstat() failed”+ e.getMessage());
}
} else {
BufferedReader reader = null;
try {
Process process = Runtime.getRuntime().exec(("ls -il " + path));
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);
}
process.waitFor();
String ret = output.toString();
if (!TextUtils.isEmpty(ret)) {
ret = ret.trim();
String[] splitArr = ret.split("\\s+");
if (splitArr.length>0) {
inode = splitArr[0];
}
}
} catch(Exception e) {
Log.e(TAG, "!!! Runtime.getRuntime().exec() exception, cmd:”+cmd);
} finally {
if (reader != null) {
try {
reader.close();
} catch (IOException e) {}
}
}
}
return inode;
}

Android Runtime.getRuntime().exec and rsync

I'm tryng to run rsync on my device. I have the binary in /system/xbin/rsync and I'm trying to launch it with Runtime.getRuntime().exec. I'm new to Android programming, so I don't get yet if I have to user Superuser Permissions.
My code is:
try {
Process process = Runtime.getRuntime().exec(
"/system/xbin/rsync -avzru /sdcard/Tinybox/ " +
"mattiazeni#192.168.1.6::88124bb378ac994088e704d553de6f19");
System.out.print("RSYNC LAUNCHED\n");
// Reads stdout.
// NOTE: You can write to stdin of the command using
// process.getOutputStream().
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();
System.out.print(output);
System.out.print("RSYNC FINISHED\n");
// return output.toString();
} catch (IOException e) {
throw new RuntimeException(e);
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
And it doesn't work, it just prints "RSYNC STARTED" "RSYNC FINISHED".
But if I run:
Process process = Runtime.getRuntime().exec("/system/xbin/rsync --help");
it works fine, I can see the output from the LogCat window.
So I guess I have to use Superuser Permissions and so I modified my code as follows:
try {
System.out.print("RSYNC STARTED\n");
Process process = Runtime.getRuntime().exec("/system/xbin/su");
DataOutputStream os = new DataOutputStream(process.getOutputStream());
DataInputStream is = new DataInputStream(process.getInputStream());
os.writeBytes("/system/xbin/rsync --help");
String output = new String();
String temp = new String();
output = is.readLine();
System.out.print(output);
os.flush();
System.out.print("RSYNC FINISHED\n");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
}
But when I run the code the App freezes with no errors.

Ok, I'm using a slightly different version of the code:
try {
System.out.print("RSYNC STARTED\n");
process = Runtime.getRuntime().exec("/system/xbin/su -c sh");
OutputStream os = process.getOutputStream();
Log.d("RSYNC","/system/xbin/rsync" + " -avzru /sdcard/download/ mattiazeni#192.168.1.6::TinyBox &");
writeLine( os, "/system/xbin/rsync" + " -avzru /sdcard/download/ mattiazeni#192.168.1.6::TinyBox &");
os.flush();
System.out.print("RSYNC FINISHED\n");
}
catch ( IOException e ) {
e.printStackTrace();
}
I understood that the problem is on the su command. If I launch rsync using su it blocks with no error message as I previously said, if I remove the su command and launch just:
try {
System.out.print("RSYNC STARTED\n");
process = Runtime.getRuntime().exec("sh");
OutputStream os = process.getOutputStream();
Log.d("RSYNC","/system/xbin/rsync" + " -avzru /sdcard/download/ mattiazeni#192.168.1.6::TinyBox &");
writeLine( os, "/system/xbin/rsync" + " -avzru /sdcard/download/ mattiazeni#192.168.1.6::TinyBox &");
os.flush();
System.out.print("RSYNC FINISHED\n");
}
catch ( IOException e ) {
e.printStackTrace();
}
it works fine, but of course I got an error from rsync because I have no permissions and the synchronization won't work. How can I solve my problem??

Getting output from busybox commands within Android app

For the life of me, I can't get my app to get the response from a process calling busybox from within su shell.
I've tried three different methods, as well as tried a combination of the three to get it to work, but I can never get the output from anything using busybox, only the rest of the commands.
To be more specific, I can get it to return commands like ls /data and cat suchandsuch.file, but anything that starts with "busybox" (i.e. busybox mount, busybox free) just won't show anything.
This was the method that got the closest for me, this code works with ls /data, but not "busybox free"
This one would run the command (for the most part), and return an empty string instead of loop endlessly from the inputstream.
Process p;
try {
p = Runtime.getRuntime().exec(new String[]{"su", "-c", "/system/bin/sh"});
DataOutputStream stdin = new DataOutputStream(p.getOutputStream());
stdin.writeBytes("ls /data\n");
DataInputStream stdout = new DataInputStream(p.getInputStream());
byte[] buffer = new byte[4096];
int read = 0;
String out = new String();
while(true){
read = stdout.read(buffer);
out += new String(buffer, 0, read);
if(read<4096){
break;
}
}
Toast.makeText(getApplicationContext(), out, Toast.LENGTH_SHORT).show();
} catch (IOException e) {
e.printStackTrace();
}
The toast near the bottom shows everything from ls /data, but when changed to anything for busybox, its blank or null.
I've also tried both of these, but neither of them worked. (I was passing the process to them after the command was run.)
Both of these would always result in the app freezing right when you hit the button for the methods.
String termReader(Process process){
BufferedReader reader = new BufferedReader(
new InputStreamReader(process.getInputStream()));
try {
int i;
char[] buffer = new char[4096];
StringBuffer output = new StringBuffer();
while ((i = reader.read(buffer)) > 0)
output.append(buffer, 0, i);
reader.close();
return output.toString();
} catch (IOException e) {
e.printStackTrace();
return e.getMessage();
}
}
String processReader(Process process){
InputStream stdout = process.getInputStream();
byte[] buffer = new byte[1024];
int read;
String out = new String();
while(true){
try {
read = stdout.read(buffer);
out += new String(buffer, 0, read);
if(read<1024){
break;
}
} catch (IOException e) {
e.printStackTrace();
}
}
return out;
}
There's no stack traces to work with, so I'm starting to get a bit stumped.
Edited with the code proposed below, uhm, below :D
I changed it around a small bit to make it a oneclick run thing for easier troubleshooting and testing.
This also freezes when it tries to read the inputstream, and if I call stdin.writeBytes("exit\n") before trying to read the stream it gives me the blank answer from closing the terminal, if I call it after, it loops endlessly.
void Run() {
String command = "busybox traceroute\n";
StringBuffer theRun = null;
try {
Process process = Runtime.getRuntime().exec("su");
DataOutputStream stdin = new DataOutputStream(process.getOutputStream());
stdin.writeBytes(command);
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) {
theRun = output.append(buffer, 0, read);
}
reader.close();
process.waitFor();
} catch (IOException e) {
throw new RuntimeException(e);
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
Toast.makeText(getApplicationContext(), theRun, Toast.LENGTH_SHORT).show();
}
It seems like its skipping the first line (the busybox info line you get every time you invoke the command) and not catching the rest of the data. Ive tried all variations I can think of to get this working right :/
If anybody's got some insight on this, I'd be greatly appreciative :)

Here is a quick solution... It is a utility class I created just for this. You can use the native shell, a root shell if the device is rooted, or set a custom shell. Here you go.
https://github.com/jjNford/android-shell

I've found a sort of a workaround for this.
First of all, running commands linked to busybox in my case would never return their output through their InputStream, no matter what method I tried (And I tried ALOT lol).
This is what I found out I could do. It's a bit tedious, and doesn't give you the full output, but if you want something to rely on whether a command fired off properly (in my case, my app just wouldn't work right if I couldn't compare how everything ran.)
You cant get the input from the process, but you CAN get the exit value if you work it right :) this works for anything that doesn't give you a complex response (like using cat on a large file)
The difference between the two is easy to find, for instance:
command = "cat /sys" // works, exits with 1
command = "cat /init.rc" doesnt work, exits with 0
This is how I set it up to work easily. Run the commands as normal using the method provided by MasterJB:
process p;
try {
p = Runtime.getRuntime().exec(new String[]{"su", "-c", "/system/bin/sh"});
DataOutputStream stdin = new DataOutputStream(p.getOutputStream());
stdin.writeBytes(command);
stdin.writeBytes("echo $?\n");
DataInputStream stdout = new DataInputStream(p.getInputStream());
byte[] buffer = new byte[4096];
int read = 0;
String out = new String();
while(true){
read = stdout.read(buffer);
out += new String(buffer, 0, read);
if(read<4096){
break;
}
// here is where you catch the error value
int len = out.length();
char suExitValue = out.charAt(len-2);
Toast.makeText(getApplicationContext(), String.valueOf(suExitValue), Toast.LENGTH_SHORT).show();
return0or1(Integer.valueOf(suExitValue), command); // 0 or 1 Method
// end catching exit value
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
I also found it easier to make a "0 or 1" method to return what happened. In this example it's fired as a toast. You may also want to test if the char is actually an integer, as some commands give no exit value whatsoever (weird, I know. One instance is ls /sys, this returns a blank exit value when run through a su terminal.)
String return0or1 (int returnValue, String command){
String message = command + " - Cannot get return value.";
if (returnValue == 0){
message = command + " - successful.";
return message;
}
if (returnValue == 1){
message = command + " - failed.";
return message;
}
return message;
}
With a little bit of research you can match just about any exit value with proper responses, just gotta capture them right :)
These methods return just whether the command ran (0), but if it gets a double or triple char exit code, the last digit may be 0 when it failed (i.e. when exit value is 10), so this will work in most cases, but needs to be expanded upon to catch double and triple values.

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.

How can we execute a shell script file from my Android Application

Please Tell me it is possible to run a shell script file from My Android application.
and read the data from script file.
If it is possible than how to proceed , Please give me some guideline.

You can use this code snippet (from Aaron C)
void execCommandLine(String command)
{
Runtime runtime = Runtime.getRuntime();
Process proc = null;
OutputStreamWriter osw = null;
try
{
proc = runtime.exec("su");
osw = new OutputStreamWriter(proc.getOutputStream());
osw.write(command);
osw.flush();
osw.close();
}
catch (IOException ex)
{
Log.e("execCommandLine()", "Command resulted in an IO Exception: " + command);
return;
}
finally
{
if (osw != null)
{
try
{
osw.close();
}
catch (IOException e){}
}
}
try
{
proc.waitFor();
}
catch (InterruptedException e){}
if (proc.exitValue() != 0)
{
Log.e("execCommandLine()", "Command returned error: " + command + "\n Exit code: " + proc.exitValue());
}
}
But this requires root access I think.
You could also try to use GScript

I've been using this to run shell scripts in my android app. Only thing I've yet to figure out how to do is direct the output to where I want it. You don't need root for this, which is why I'm posting.
Process process = Runtime.getRuntime().exec("top -n 1");
//Get the output of top so that it can be read
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(process.getInputStream()));