Trying to learn Linux command-line as fast as possible, know of any online test that progressively present questions requiring a command be entered. Looking for test that recall what I've answered, and not answered -- and that present command-line based questions based on frequency of command-line operation and it's methods used in the real world.
closed as not constructive by sysadmin1138♦ Feb 7 '12 at 22:40
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You... don't really need one. Just install and use Linux. It's free, and there are free virtualization solutions available as well.