Ubuntu 安装 Oracle11g 后 重启不能启动解决方式参考
Just remember: this script depends on the existence of a database on the machine, so don’t forget to run dbca as the oracle user, and configure it to start at boot time (edit /etc/oratab after creating the database, and set the last column to Y).

link:http://www.pythian.com/news/968/installing-oracle-11g-on-ubuntu-804-lts-hardy-heron/