What is daemon process?

A daemon is a program that runs in background and has no controlling terminal. They are often used to provide background services. For example, a web-server or a database server can run as a daemon.

When a daemon process is initialized:

• It creates a child of itself and proceeds to shut down all standard descriptors (error, input, and output) from this particular copy.
• It closes the parent process when the user closes the session/terminal window.
• Leaves the child process running as a daemon.

Daemonize Node.js process:

• Forever
• PM2
• Nodemon
• Supervisor
• Docker

Example: Using an instance of Forever from Node.js

const forever = require("forever");

const child = new forever.Forever("your-filename.js", {
  max: 3,
  silent: true,
  args: [],
});

child.on("exit", this.callback);
child.start();