What is daemon

Taking your first steps as a Linux sysadmin? Here are the OS hardening tricks you need to secure your systems. Bobby is a technology enthusiast who worked as a software developer for most of two decades.

What Is a Daemon? Share Share Tweet Email. Bobby Jack 61 Articles Published. Subscribe to our newsletter Join our newsletter for tech tips, reviews, free ebooks, and exclusive deals! Click here to subscribe. The 7 Best Smart TVs in Safari vs. Kali Linux vs. BackBox vs. Another useful thing to do with make is to restart a daemon. The spooling daemon uses the appropriate filters to print the data accordingly.

In addition, the sniffer chooses a random protocol and sends the packet to the logging daemon. Then you have to go fetch and install an ARP daemon. All rights reserved. Filters 0. Words form: daemons. See word origin. A guardian spirit; inspiring or inner spirit. Interactive processes are those which are run by a user at the command line are called interactive processes. Batch processes are processes that are not associated with the command line and are presented from a list of processes.

These are best at times when the system usage is low. When I was a full-time system administrator, I often ran disk usage inventories, system behavior analysis scripts, and so on, at night. Interactive processes and batch jobs are not daemons even though they can be run in the background and can do some monitoring work. They key is that these two types of processes involve human input through some sort of terminal control.

Daemons do not need a person to start them up. We know that a daemon is a computer program that runs as a background process, rather than being under the direct control of an interactive user. When the system boot is complete, the system initialization process starts spawning creating daemons through a method called forking , eliminating the need for a terminal this is what is meant by no controlling terminal. I will not go into the full details of process forking, but hopefully, I can be just brief enough to show a little background information to describe what is done.

While there are other methods to create processes, traditionally, in Linux, the way to create a process is through making a copy of an existing process in order to create a child process.

An exec system call to start another program in then performed. It gets its name from the C programming language. One of the libraries that C uses, is called the standard library, containing methods to perform operating services.

One of these methods, called fork , is dedicated to creating new processes. The process that initiates a fork is considered to be the parent process of the newly created child process. The process that creates daemons is the initialization called init process by forking its own process to create new ones. Done this way, the init process is the outright parent process.

There is another way to spawn a daemon and that is for another process to fork a child process and then die a term often used in place of exit. When the parent dies, the child process becomes an orphan. When a child process is orphaned, it is adopted by the init process. It is important that you do not confuse this with a zombie. Remember, a zombie is a child process that has finished its task and is waiting on the parent to accept the exit status.

Again, the most common way to identify a Linux daemon is to look for a service that ends with the letter d. Here are some examples of daemons that may be running on your system. You will be able to see that daemons are created to perform a specific set of tasks:. This is a newer version of syslogd having several additional features. It supports logging on local systems as well as on remote systems.

This is normally run with Web server software such as Apache. This is used on virtually any server that accepts SSH connections.

When I first started writing this article, I planned to only cover what a daemon is and leave it at that.