search_attachments.module allows searching the text of PDF, MS Word, plain text, and other types of files attached to nodes. In order to extract the text from attached files, this module calls 'helper apps' such as cat and pdftotext. Drupal administrators can configure any helpers they like.
This module is no longer supported as it has been combined with Search Files. Please refer to the Search Files module which now includes the Search Attachments module.