Perhaps there are some online courses posted to youtube, or a few books that someone might like to recommend? I would be interested to know what types of things one must learn to get "linux-certification" (I presume there is such a thing).
I have learned much about the Linux kernel be reading this book: "Understanding the Linux Kernel" by Daniel P. Bovet and Marco CesatiIt's very big, but there is everything in it what you would like to know about Linux.
Greetings, Oliver Verlinden