As Linux system administrator every once in a while you need to install something requiring Java. Open-source guys tend to gear towards OpenJDK, the GPL-licensed version of java. Still, java developers tend to write a lot of crappy code requiring a specific version of run-time-engine. So, you're in a desperate need of Oracle's java.
Now the Oracle people are very keen on you accepting their license before you can get your hands on their precious, leaky, JRE. At the same time all you have in front of you is a Bash-prompt and you're itching to go for a: