Where to test your linux knowledge?

Hello here!

I am trying to widen my knowledge about Linux : managing the system (network, storage , process , etc..) , how to solve systems problems, Deepen my understanding of the system and use new command or paradigm for example

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Do you have any good website or other sources , that , you think my be helpful?

Ideally , I am looking for a "katakoda" like website , where you have a given question , and have access to a test server , to try and solve the problem.

If it doesn't exist do you have have a website/github where problems or questions are asked ? (I can use my own computer , VM , Free tier EC2, or Raspberry).

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I am starting a new job next month , I learned a lot about DevOps related subject from past experience , but now I want to have a better/deeper understanding of Linux.

Thanks in advance for you help , and have a great Day/Night !