If you are asking for where the tomcat6 looks for which files to serve (by default):
/var/lib/tomcat6/webapps
the ROOT directory should be your default context and you can define other context's there as well (ex: hudson).
To install Railo onto the built in tomcat you can place the war file from the Railo site into the webapps dir and it will auto-expand. If you change the name of the war before you copy it to be ROOT.war it will deploy to the ROOT context of the tomcat server.
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Randy Merrill