There's a saying - 'The devil is at his strongest while we're looking the other way.'

Like a program running in the background silently. While we're busy doing other shit. 'Daemons,' they call them. They perform action without user interaction. Monitoring, logging, notifications....

What Are Daemons?

Pronounced as day-mons. Daemons are processes that run in the background. They are usually used to perform tasks that are not directly related to the user. For example, a daemon might be used to monitor a network connection and log the traffic.

Identifying Your Daemons

A simple way of identifying daemons on your linux system is to run the pstree command.

pstree

Summoning Your Daemons

You can summon your daemons by running the service command.

service <daemon> start
service <daemon> stop
service <daemon> restart
service <daemon> status

Want to spin up a daemon?

sudo systemctl start <daemon>
sudo systemctl stop <daemon>
sudo systemctl restart <daemon>
sudo systemctl status <daemon>

Finally using systemd you can manage your daemons. A quick boot up daemon example has already been published by me here - Running Scripts On Boot.

Final Thoughts

A quick way to identify daemons even includes looking at the suffix of services. If it ends with a d it's a daemon.

Examples:

• mysqld
• systemd
• httpd
• sshd