For the standard library (POSIX), I don't have a good catch all source but you'll want one here.
For networking (which tells more than just networking), "Beej's Guide to Networking". That's a fantastic book (online free from the author). Hilarious and informative.
I liked writing existing unix utilities myself and I found that a helpful set of projects.
> An attempt will be made to find how to make machines use language, form abstractions and concepts, solve kinds of problems now reserved for humans, and improve themselves. We think that a significant advance can be made in one or more of these problems if a carefully selected group of scientists work on it together for a summer.
I normally do intermittent fasting and stay away from carbs during the work week. I don't do buffet and usually don't have 2 daily meals, let alone 3.
So, after 2-3 days of repeating the feast -3 times a day-, my stomach and intestines finally went on strike. I ended up with a strong reaction with a loose stool. 2 days later, it would still not go away. It was constant. I was chained to the bathroom. The rest of the family didn't overeat + mix everything, so naturally they were totally fine.
Finally on the 3rd day, I gave up on waiting it out and asked for help from our jungle guide.
He told me to have oregano tea, so had 2 cups. The change was instantaneous. Just like the article, all the locals from the amazon knew this was the standard remedy for diarrhea.
I googled this afterwards. None of the top hits for home remedy for diarrhea even mentioned oregano tea once in their articles. A medical dietitian had a 1 word link back to diarrhea in a "oregano health benefits" article [1].
Its crazy how ignorant we are of natural methods, and makes me wonder what other wonderful natural medicines are waiting to be re-discovered in the amazon.