How to run rename shell command in android app (rooted)

Question

I'm new to Android. I'm trying to run a shell command to rename a file in the system. I've got root access to it.

The shell command:

$ su
# mount -o remount,rw /system
# mv system/file.old system/file.new

I have tried this but doesn't work:

public void but1(View view) throws IOException{
    Process process = Runtime.getRuntime().exec("su");
    process = Runtime.getRuntime().exec("mount -o remount,rw /system");
    process = Runtime.getRuntime().exec("mv /system/file.old system/file.new");
}

Answer 1

You can run more then one command using the same process, by writing the commands in the process's OuputStream . This way the commands will run in the same context that the su command is running. Something like:

Process process = Runtime.getRuntime().exec("su");
DataOutputStream out = new DataOutputStream(process.getOutputStream());
out.writeBytes("mount -o remount,rw /system\n");
out.writeBytes("mv /system/file.old system/file.new\n");
out.writeBytes("exit\n");  
out.flush();
process.waitFor();

Answer 2

You need each command to be in the same process as su , since the switch to root doesn't apply to your application, it applies to su , which completes before you get to mount .

Instead, try two exec's:

...exec("su -c mount -o remount,rw /system");
...exec("su -c mv /system/file.old system/file.new");

Also, be aware that I've seen some systems where the mount -o remount,rw /system would fail however mount -o remount,rw /dev/<proper path here> /system would succeed. The "proper path here" is different from one manufacturer to the next, but it can be programatically gathered.