title: Unmount USB Drive/Sdcard programatically Android (Have Root Access)
body: <p>I am trying to unmount the sdcard/usb drive programatically from Android JellyBean device. I have the mountpaths for them. /mnt/udisk and /mnt/extsd respectively. I have SuperUser Access. 
  I have tried running the following code but does not give me the results:</p>
  
  <pre><code>           Process su = null; 
              try { 
                  su = Runtime.getRuntime().exec("su");
                  String cmd = "umount /mnt/extsd/"+ "\n";
                  su.getOutputStream().write(cmd.getBytes());
                  String exit = "exit\n";
                  su.getOutputStream().write(exit.getBytes());
                  su.waitFor();
                  Toast.makeText(MyAndroidAppActivity.this, "Completed", Toast.LENGTH_LONG).show();
              } catch (Exception e) {
                  e.printStackTrace();
                  Toast.makeText(MyAndroidAppActivity.this, e.toString(), Toast.LENGTH_LONG).show();
              } finally { 
                  if (su != null) { 
                      su.destroy(); 
                  } 
  </code></pre>