title: update/overwrite acl for a file(object)in amazon s3
body: <p>I have an option to upload the files into Amazon s3 in my website. When the user uploads the file, I am setting the acl using the <code>putObjectFile</code> function.</p>
  
  <p>In EditMode: How do I overwrite/update the acl for the file that I am updating without reuploading the file?</p>
  
  <p>Is there any function which updates the acl of the exsisting file (object).</p>
  
  <p>The solution is needed in PHP. Any links to sample code/or any other solutions are appreciated.</p>