Install OLAT as described in the installation chapter but DON'T RUN 'ant dbsetup'!! We recommend to move your existing installation from PATH_TO_YOUR_OLAT/olat3 to PATH_TO_YOUR_OLAT/olat3.1.0 and install the 3.1 package as your new PATH_TO_YOUR_OLAT/olat3. All user data is located in the olatdata directory which should not be located in the PATH_TO_YOUR_OLAT/olat3. The olatdata directory and the database won't be changed when installing the new code.

#cd PATH_TO_YOUR_OLAT
#rm olat3 (if olat3 is a symlink, otherwise: mv olat3 olat3.1.0)
#unzip OLAT-3.1.2.zip
#ln -s OLAT-3.1.2-FINAL-XXXXX olat3
#cd olat3
#vi build.properties
#ant config-all
#ant install

Update your database manually according to PATH_TO_YOUR_OLAT/olat3/database/alter_3_1_0_to_3_1_1.sql (there are no updates from 3.1.1 to 3.1.2, the 3.1.1 was never made public)

Now start tomcat. The first launch might take some time.