Install liboop4 by entering the following commands in the terminal:
sudo apt update sudo apt install liboop4
Event loop management library
Liboop is a low-level event loop management library for POSIX-based operating systems. It supports the development of modular, multiplexed applications which may respond to events from several sources. It replaces the "select() loop" and allows the registration of event handlers for file and network I/O, timers and signals. Since processes use these mechanisms for almost all external communication, liboop can be used as a basis for almost any application.