title: execute "su" failed in my fully rooted Android device
body: <p>while i add this line to my code</p>
  
  <pre><code>Process process = Runtime.getRuntime().exec("su -c");
  </code></pre>
  
  <p>or</p>
  
  <pre><code>Process process = Runtime.getRuntime().exec("su");
  </code></pre>
  
  <p>trying to run the"su" command,</p>
  
  <p>process.exitValue() returns 1 which means fail.</p>
  
  <p>This happens to my one Android device while my the other rooted android device works perfectly with this command. (process.exitValue() returns 0)</p>
  
  <p>Can anyone teach me how to trace the error or how to fix it?</p>
  
  <p>I am confused with this error while my two devices almost in the same condition.</p>
  
  <p>Thanks for your reply in advance.</p>
  
  <hr>
  
  <p>Hi guys,</p>
  
  <p>Thanks for discussing this issue with me. Your reply hints me a clue that I have removed my old su and place a new su. Luckily enough, the return value is now 0 and I guess it means correct. However, Does any of you might know what is the difference between .exec("su -c") and .exec("su")? Please let me know if you know the difference. </p>