What are some good online resources for learning C?

I have a fundamental knowledge of C and I am wanting to get better at understanding C. here is an example of what I'm looking for. I write random programs to try and challenge my self with help from the man pages, for example i'm trying to create my own Linux shell right now, but I feel as i'm just using functions and not understanding what's happening when I use them, the article that I linked helped me understand what was going on with scanf and fgets more, and I'm looking for similar articles.