android : how to run a shell command from within code

Question

I am trying to execute a command from within my code, the command is "echo 125 > /sys/devices/platform/flashlight.0/leds/flashlight/brightness" and I can run it without problems from adb shell

I am using Runtime class to execute it :

Runtime.getRuntime().exec("echo 125 > /sys/devices/platform/flashlight.0/leds/flashlight/brightness");

However I get a permissions error since I am not supposed to access the sys directory. I have also tried to place the command in a String[] just in case spaces caused a problem but it didn't make much differense.

Does anyone know any workaround for this ?

Answer 1

I think the device will need to be "rooted" for this to work. Have a search on google and see how other developers have dont this, there is no shortage of flashlight apps.

Answer 2

Agreed you probably need to root the phone to write to system files. I'm surprised the brightness isn't exposed through the SDK.

For details on running shell commands from code, check out this project: http://code.google.com/p/android-log-collector/source/browse/trunk/android-log-collector/src/com/xtralogic/android/logcollector/SendLogActivity.java

Answer 3

The phone needs to be rooted, afterwards you can do something like:

public static void doCmds(List<String> cmds) throws Exception {
    Process process = Runtime.getRuntime().exec("su");
    DataOutputStream os = new DataOutputStream(process.getOutputStream());

    for (String tmpCmd : cmds) {
            os.writeBytes(tmpCmd+"\n");
    }

    os.writeBytes("exit\n");
    os.flush();
    os.close();

    process.waitFor();
}    

Answer 4

If you're just trying to set brightness, why don't you do so through the provided API (AKA, is there a reason you are trying to do it the way you are).

int brightness = 125; 
Settings.System.putInt(
      ftaContext.getContentResolver(), 
      Settings.System.SCREEN_BRIGHTNESS, 
      brightness); 

Answer 5

Did you find a solution to this?

It's certainly possible. I have found at least one app that could do it. I have been searching a way to do it all night too, without success.