code: def _ProcessGrepSource(self, source):
      
      attributes = source.base_source.attributes
      paths = artifact_utils.InterpolateListKbAttributes(
          attributes["paths"], self.knowledge_base,
          self.ignore_interpolation_errors)
      regex = utils.RegexListDisjunction(attributes["content_regex_list"])
      condition = rdf_file_finder.FileFinderCondition.ContentsRegexMatch(
          regex=regex, mode="ALL_HITS")
      file_finder_action = rdf_file_finder.FileFinderAction.Stat()
      request = rdf_file_finder.FileFinderArgs(
          paths=paths,
          action=file_finder_action,
          conditions=[condition],
          follow_links=True)
      action = file_finder.FileFinderOSFromClient
  
      yield action, request
docs: Find files fulfilling regex conditions.