# Hide configuration and passwd files from view
  HideFiles "(\\.conf|passwd)$"

  # ...or the same regex, without the quotes
  HideFiles (\.conf|passwd)$

  # Hide those same files from everyone _except_ a special user
  HideFiles (\.conf|passwd)$ user !tj

  # Using the ! prefix to "invert" the regular expression matching,
  # allow only .txt and .html files to be seen
  HideFiles !(\.txt|\.html)$

  # Only let users of the webmaster group see HTML files, but nothing else
  HideFiles !(\.htm|\.html)$ group webmaster