A daemon is a program that runs without direct user interaction and runs as a background process of an operating system (OS).
According to a programmer who was a part of the Massachusetts Institute of Technology’s (MIT)’s Project MAC in 1963, the term came from Maxwell’s demon, a thought experiment meant to disprove the second theory of thermodynamics. The term “daemon” also comes from the Greek word “daimōn,” which refers to a spirit or divine being. This name reflects its role in working quietly behind the scenes.
Daemons are crucial for maintaining the smooth operation of IT infrastructures. They automate routine tasks, ensure the availability of critical services, and enhance the overall efficiency and reliability of computer systems.
Here are some characteristics common to most daemons:
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Background operation
Daemons are designed to run in the background and perform various tasks without user intervention.
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Independence
They start at system boot time or when needed and continue running independently of any user session.
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Services provision
Daemons provide essential services such as handling network requests, managing hardware devices, and executing scheduled tasks.
How do daemons work?
Daemons typically start during the system’s boot process, either initiated by startup scripts or by the system’s init process. Once a daemon has started running, it usually runs indefinitely, awaiting specific events or conditions to perform its tasks.
What is a daemon in Linux?
Daemons are commonly utilized by Unix-like systems such as Linux operating system (OS) devices. On Linux systems, systemd is typically the first daemon that starts running upon the system booting up and is the last to terminate when the device shuts down.
What is a daemon in Windows?
When it comes to Windows OS devices, daemons are instead known as “services.” By utilizing the Service Control Manager, they can be configured to start at boot or to start only up and stop through manual intervention.
What are the types of daemon?
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Device daemons
These daemons manage processes tied to specific devices, such as Virtual Reality devices or Bluetooth connections.
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System daemons
These daemons handle functions of the OS, such as time synchronization.
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Network daemons
These daemons manage networks such as the named daemon, which allows DNS to function. Users can use commands via this daemon to see DNS information
What are some common examples of daemon?
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Web servers
These daemons handle incoming web requests and serve web pages to users. An example is the Apache HTTP server daemon, which runs in a web server’s background and responds to network requests.
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Mail servers
Mailing daemons manage the sending, receiving, and storage of email messages. One of the most common examples of this kind of daemon at work is when users’ email delivery fails, and the daemon sends a message notifying them of the failure alongside an error code to describe what went wrong.
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cron daemon on Linux
One of the most commonly used daemons in Linux is cron, which executes scheduled tasks at specified intervals through crontab files.
Conclusion
Daemons are indispensable programs that allow devices, networks, and servers to function efficiently. While they work in the background, they are essential for multitasking processes and performing various tasks associated with automation or managing a device’s resources.
