The Sockets Networking API: UNIX® Network Programming Volume 1, Third Edition

Chapter 13. Daemon Processes and the inetd Superserver

Introduction

A daemon is a process that runs in the background and is not associated with a controlling terminal. Unix systems typically have many processes that are daemons (on the order of 20 to 50), running in the background, performing different administrative tasks.

The lack of a controlling terminal is typically a side effect of being started by a system initialization script (e.g., at boot-time). But if a daemon is started by a user typing to a shell prompt, it is important for the daemon to disassociate itself from the controlling terminal to avoid any unwanted interraction with job control, terminal session management, or simply to avoid unexpected output to the terminal from the daemon ...