title: permission denied - php unlink
body: <p>I have two files:
  b.php and test.txt</p>
  
  <pre><code>&lt;?php 
  $b = "test.txt";
  unlink($b);
  ?&gt;
  </code></pre>
  
  <p>and the error is: Warning: unlink(test.txt) [function.unlink]: Permission denied</p>
  
  <p>why? b.php and test.txt is 777 and the same group/login</p>
  
  <p>if I set 777 on the parent directory I can execute unlink but i have to set 777 and back to 755? </p>