| 1 system.api.php | hook_file_update(File $file) | 
Respond to a file being updated.
This hook is called when an existing file is saved.
Parameters
File $file: The file that has just been updated.
Related topics
File
- core/modules/ system/ system.api.php, line 2372 
- Hooks provided by Backdrop core and the System module.
Code
function hook_file_update(File $file) {
  $file_user = user_load($file->uid);
  // Make sure that the file name starts with the owner's user name.
  if (strpos($file->filename, $file_user->name) !== 0) {
    $old_filename = $file->filename;
    $file->filename = $file_user->name . '_' . $file->filename;
    $file->save();
    watchdog('file', t('%source has been renamed to %destination', array('%source' => $old_filename, '%destination' => $file->filename)));
  }
}
