Definition
A daemon is a computer program that runs in the background of a multitasking operating system. It doesn’t need user control, so the user doesn’t have to activate it to start running. Usually, a certain action or event starts a daemon program.
For instance, it runs software or services on a server in the background. If a particular service is installed on a server, a daemon also runs in the background.
Daemons are Linux or Unix programs implemented to respond to requests for specific hardware services and activities through other systems on the network and reply to requests from other programs.
Common Daemon Programs
- Cron Daemon (crond): A crond is a job scheduler that initiates specific actions at scheduled times.
- httpd: A httpd expects and responds to incoming requests sent from its web server.
- OpenSSH Daemon (sshd): This daemon listens to the secure shell protocol to process incoming requests.
- SMTP or mailer-daemon (sendmail): This daemon manages the email automation on a specific system or server.
- mysqld: A mysqld daemon stops and initiates a MySQL database server.