code: public static String path2unix(File file)
    {
      return file != null ? path2unix(file.getPath()) : null;
    }
docs: Convert a file to an Unix like path string. This method just delegates {@link #path2unix(String)}. Returns null if
  <code>file</code> parameter is null.
  
  @param file file to convert.
  @return Unix like path string.