Everything with Unix sits on the foundation that multiple users from various terminals (requiring different driver implementations) are typing text on them simu

Everything with Unix sits on the foundation that multiple users from various terminals (requiring different driver implementations) are typing text on them simultaneously. The system consists of little programs that users combine in creative ways to run a process hierarchy. And this is temporally-confined within a session, so nothing of that “playing” should remain running once the session is over, unless explicitly stated with setsid() and friends.