### epoll() Tutorial – epoll() In 3 Easy Steps!
https://www.suchprogramming.com/epoll-in-3-easy-steps/
http://matrix207.github.io/2014/04/10/epoll-example-in-c/
### how-to-use-epoll-a-complete-example-in-c
https://banu.com/blog/2/how-to-use-epoll-a-complete-example-in-c/epoll-example.c
https://stackoverflow.com/questions/51777259/how-to-code-an-epoll-based-sockets-client-in-c
https://www.cnblogs.com/fnlingnzb-learner/p/5835573.html