install and uninstall rpm packages under Linux

Install a given rpm package. –force overwrites the package if it is already installed

rpm -i --force myrpm.rpm 

List installed rpm packages (-qa: query all)

rpm -qa

Find the exact name of an installed rpm package

rpm -qa | grep java

Uninstall the Java package in one step by using a subcommand.

rpm -e `rpm -qa | grep $PKG`

uninstall package without using scripts. This is useful if the package won’t uninstall when trying to uninstall it normally. Afterwards the package is not listed anymore by rpm -qa

rpm -e mypackage --noscripts

Installing Java under Red Hat Enterprise Linux 5

 yum install java 

To export your JDK (i.e. set your environment variable) for applications like Tomcat:

export JAVA_HOME=/usr/lib/jvm/jre-1.6.0-openjdk.x86_64/ 

To start Tomcat you need to make the sh-scripts executable, e.g. execute in your tomcat/bin directory

 chmod 774 *.sh