Here is one of my experiences I want to share, regarding Debian Linux and Dspace.
After working a day on Dspace and its cache directory in Tomcat, I realized that there is a cache directory of Dspace JSP pages. If you want modified JSP pages (in the installation directory of Dspace) to take affect, you should delete their cache in the following directory:
/var/lib/tomcat6/work/Catalina/localhost
For example, if you want to see new modified jspui/display-item.jsp
in the browser, you should first delete /var/lib/tomcat6/work/Catalina/localhost/jspui
directory by:
rm -rf /var/lib/tomcat6/work/Catalina/localhost/jspui