On start up, the portal loads many default options that configure the portal's behaviour and enables or disables certain features. These properties are loaded from files on the class path called portal.properties and system.properties. The files can be found in the directory TOMCAT_HOME\common\classes. You can overide these files by adding properties to the file portal-ext.properties. Some properties that you can add to portal-ext.properties are listed below.

Default Location for Document Library

    dl.root.dir=/home/liferay/documentlibrary/root/
    dl.version.root.dir=/home/liferay/documentlibrary/vroot/

Default Location for Jackrabbit

    jcr.jackrabbit.repository.root=/home/liferay/jackrabbit

Default Location for Auto Deployment

    auto.deploy.deploy.dir=/home/liferay/deploy

Default Location for Lucene

    lucene.dir=/home/liferay/lucene/

Default Theme and Color Scheme

    default.theme.id=classic
    default.color.scheme.id=01

Log all the Paths a User Clicks

    log.user.paths=true

These are just a few properties that can be customized in the portal-ext.properties file. Go to the file portal.properties to see all the properties.