title: Permission denied when trying to run systrace
body: <p>I'm trying to run the new systrace tool provided by the Android SDK.  As demoed during Google I/O 2012 (<a href="http://youtu.be/Q8m9sHdyXnE?t=31m4s" rel="nofollow">Demo starts at 31:04 in the video</a>) (<a href="http://youtu.be/Q8m9sHdyXnE?t=32m4s" rel="nofollow">Terminal commands demoed at 32:04</a>). . </p>
  
  <p>However, when I try to run the command (in Terminal on a Mac) I get the following:</p>
  
  <pre><code>-bash: ./systrace.py: Permission denied
  </code></pre>
  
  <p>What am I doing wrong?</p>
  
  <p>Thanks</p>