Runs a shell command of your choice to install the tool. Ubuntu example, assuming the Jenkins user is in /etc/sudoers:

sudo apt-get --yes install openjdk-6-jdk

(In this case specify /usr/lib/jvm/java-6-openjdk as the home directory.)

As another example, to install Sun JDK 6 for (x86) Linux, you can use DLJ:

bin=jdk-6u13-dlj-linux-i586.bin
if [ \! -f $bin ]
then
    wget --no-verbose http://download.java.net/dlj/binaries/$bin
    sh $bin --unpack --accept-license
fi

(In this case specify jdk1.6.0_13 as the home directory.)