T44 Dec 24, 2025 2 min read

Daemon

A long-running background service process, typically started by the OS or a supervisor rather than an interactive user.

Definition

A daemon is a long-running background process that provides a service.

Unlike an interactive process, a daemon is usually started by the OS at boot, or by a supervisor, and it keeps running until it is stopped, restarted, or crashes.

What makes it operationally different

Daemons often have:

  • structured logging to files or stdout
  • configuration reload behavior (often tied to SIGHUP on Unix)
  • defined shutdown behavior (signals, graceful shutdown timeouts)