Redmine ships with a built-in documents module. Some users may not find this module satisfying their needs. In such cases, there are modules that improve this document's module functionality, or completely replace it. One such module is the Document Management System Features module.
If you want to use document-indexing and search features on the server, you need to install some additional software and libraries. To do this, open the console and type the following:
sudo apt-get install libxapian-ruby1.9.1 xapian-omega libxapian-dev xpdf antiword unzip catdoc libwpd-0.9-9 libwps-0.2-2 gzip unrtf catdvi djview djview3 uuid uuid-dev