Ideas to challenge my linux college students.

So far I've had a few ideas of fun challenges to give my students. Tasks I've given them so far are to grep the man to find and find the man to grep. Make doom run on their linux vm. With absolutely no help I've also told them to find a way to the linux channel of freenode irc.

These students are just starting out and each of these tasks teach them some basic skills and gets them used to working in the terminal. What are some other tasks I can give them?