title: What is the difference between "/storage/udisk/sda4/" and "/mnt/media_rw/udisk/sda4/" in Android?
body: <p>I met a strange question, <code>/storage/udisk/sda4/</code> and <code>/mnt/media_rw/udisk/sda4/</code> should mean the same folder in android, but with the code below:</p>
  
  <pre><code>File sdcard = new File("/mnt/media_rw/udisk/sda4");
  
  Log.d(LOG_TAG, "sdcard: " + sdcard 
                  + ", exists: " + sdcard.exists());            // return false
  
  sdcard = new File("/storage/udisk/sda4");
  
  Log.d(LOG_TAG, "sdcard: " + sdcard 
                  + ", exists: " + sdcard.exists());            // return true
  </code></pre>
  
  <p>I get different result, why is this?</p>
  
  <p><code>ll /mnt/media_rw/udisk/</code> return <code>drwxrwx--- media_rw media_rw 1970-01-01 00:00 sda4</code></p>
  
  <p><code>ll /storage/udisk</code> return <code>drwxrwx--x root sdcard_r 1970-01-01 00:00 sda4</code></p>