sudo apt-get update
sudo apt-get install unzip openjdk-6-jre
echo "export JAVA_HOME=/usr/lib/jvm/java-6-openjdk-amd64" >> ~/.bashrc
source ~/.bashrc
wget -c http://sourceforge.net/projects/geoserver/files/GeoServer/2.3.5/geoserver-2.3.5-bin.zip/download
unzip -a geoserver-2.3.5-bin.zip
cd geoserver-2.3.5/bin
./startup.sh &
In web browser visit http://localhost:8080/geoserver/