A process on a Unix-based system is a userspace application executed and scheduled by the operating system. In this book, we will refer to processes and userspace applications interchangeably.
As will be shown, most Unix-based processes that are running at any given time are children of some other parent process, and each kernel implements processes under the hood differently, but the same basic commands for creating and managing processes are provided by all Unix operating systems.
In this section, we will discuss how to create and manage Unix-based processes using commonly-seen POSIX interfaces.