One of the best features of all of the epoll/poll/select functions is that they let you listen on arbitrary file descriptors uniformly. You can send events over

One of the best features of all of the epoll/poll/select functions is that they let you listen on arbitrary file descriptors uniformly. You can send events over a unix domain socket or a pipe, and just treat it as if it were a regular file. It's especially useful with stuff like signalfd or timerfd, where you can listen on sockets, handle signals, and have a timeout, with barely any additional code.