Packages providing a runtime or a development environment for the Java language all use symlinks in the /etc/alternatives directory to enable the system administrator to choose which programs to use for java, javac, javah, etc. Starting with java-common 0.23ubuntu1, the update-java-alternatives script can be used to set a bunch of jre/jdk alternatives: First, you have to decide which Java implementation to default to. update-java-alternatives --list tells about the available runtime and/or development environments. The first column shows the names to be used in for the following examples. - Set all runtime tools to point to the alternatives: update-java-alternatives --jre --set - Set all runtime tools (headless only) to point to the alternatives: update-java-alternatives --jre-headless --set - Set all runtime and development tools to point to the alternatives: update-java-alternatives --set - Set all runtime and development tools to auto mode: update-java-alternatives --auto