This is the command summary for installing Tomcat on Ubuntu Linux:

sudo apt-get install sun-java5-jdk
sudo apt-get install apache2
sudo apt-get install tomcat5
sudo apt-get install tomcat5-admin

Point Ubuntu to the newly installed Java JDK with:

sudo update-alternatives --config java

Select /usr/lib/jvm/java-1.5.0-sun/jre/bin/java.

Configure Tomcat for the Java JDK. Edit /etc/default/tomcat5 for this line:

JAVA_HOME=/usr/lib/jvm/java-1.5.0-sun/

Review the users for Tomcat in /var/lib/tomcat5/conf/tomcat-users.xml. Here is one relatively terrible way to configure the default user, tomcat:

<user username="tomcat"
    password="foo" roles="tomcat,manager,admin" />

Start Tomcat with:

sudo /etc/init.d/tomcat5 start

Test for connectivity by browsing http://localhost:8180. You can change this port number by editing the standalone server service, Tomcat-Standalone, in /usr/share/tomcat5/conf/server.xml.

Much of this summary is based on "Setting Up Tomcat 5 on Ubuntu 6.06" here:

http://blixtra.org/blog/2006/07/14/
    setting-up-tomcat-5-on-ubuntu-606/

and "Installing Java 5 JDK and Tomcat on Ubuntu (using VMWare)" here:

http://www.spaceprogram.com/knowledge/2006/
    05/installing-java-5-jdk-and-tomcat-on.html

For additional configuration details, see "Top Ten Tomcat Configuration Tips" by Jason Brittain and Ian F. Darwin here:

http://www.onjava.com/pub/a/onjava/2003/06/25/tomcat_tips.html