Daemon is the "silent gatekeeper" in the Linux operating system - running in the background to ensure all services run continuously and stably.
Daemon is a background process in the Linux operating system (and Unix in general), designed to run continuously and perform system tasks or provide services to applications and users.
In other words:
Daemon does not interact directly with the user.
Runs automatically when the system starts.
Manages important services such as network, printing, time, remote access...
| Features | Description |
|---|---|
| 🔹 Runs in the background | No interface, does not appear on the screen |
| 🔹 Automatic start | Usually runs with the system via systemd, init, rc.local… |
| 🔹 Names usually have “d” | Examples: sshd (SSH Daemon), systemd, dbus-daemon, cron |
| 🔹 Long-running | Keeps a process running continuously to listen for requests or perform periodic operations |
| 🔹 Distinct PID | Each daemon is a process with its own PID, independent of the user’s shell |
| Daemon | Role |
|---|---|
sshd |
Manages remote SSH connections |
crond |
Performs scheduled tasks (cron jobs) |
systemd |
Modern system and service manager |
dbus-daemon |
Communicates between processes in the system |
cupsd |
Manages printing |
nginx or httpd |
Web server daemon |
| Command | Purpose |
|---|---|
systemctl status sshd |
Check daemon status |
sudo systemctl start sshd |
Start daemon |
sudo systemctl stop sshd |
Stop daemon |
sudo systemctl enable sshd |
Automatically run daemon on boot |
sudo systemctl disable sshd |
Disable daemon autostart |