CODEWITHSUNDEEP
javaandroidfile-ioroot
Dunnow
Dunnow

Reputation: 414

how to write on /sys/ ? Android

I'm trying to writte on "/sys/devices/virtual/timed_output/vibrator/amp" file.

I can read it just fine, the problem is when i try to writte it.

Here's my code:

public static void writeValue(String filename, String value) {
    //FileOutputStream fos = null;
    DataOutputStream os = null;
    try {
        /*fos = new FileOutputStream(new File(filename), false);
        fos.write(value.getBytes());
        fos.flush();*/

        Process p;

        p = Runtime.getRuntime().exec("su");
        os = new DataOutputStream(p.getOutputStream());  

       os.writeBytes(value + " > " + filename + "\n");
       os.writeBytes("exit\n");

       Log.w(TAG, value + " >> " + filename);

       os.flush();           
    } catch (IOException e) {
        Log.w(TAG, "Could not write to " + filename);
    } finally {
        if (os != null) {
            try {
                os.close();
            } catch (IOException e) {
                Log.d(TAG, "Could not close " + filename, e);
            }
        }
    }
}

I'm always getting the feedback from Log.w(TAG, "Could not write to " + filename);

How do I proceed about that? Do I have to use some permissions? Has it to be all remade to match root access?

Upvotes: 1

Views: 1178

Answers (2)

thejh
thejh

Reputation: 45568

os.writeBytes(value + " > " + filename + "\n");

is wrong. Try

os.writeBytes("echo '"+value + "' > " + filename + "\n");

or

os.writeBytes("echo -n '"+value + "' > " + filename + "\n");

.

Upvotes: 0

Raghav Sood
Raghav Sood

Reputation: 82543

Normal SDK applications only have read access to that part of the system. You will need to root your device, and execute commands in a su shell to write over there.

Also, the amp file doesn't exist on all devices.

Upvotes: 3

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