daemon (computer)

A daemon, pronounced “di-moon” as a word meaning “devil” and basically “day-moon”, is a Unix/Linux program that runs inside a document, ready daemonstory.com perform an operation when needed. A daemon running as an extension of the operating system can be described as a normally automatic process that is very loud at startup.

In this process an interesting story that uses Professor Corbato’s amazing origin story, he reveals, that Damon originally had associations with “fellow…dweller or spirit” and that

At the end of the 16th century, the supernatural meaning of the word caudillo stood out behind the orthographic demon, and the evil meaning remained with the demon.

It tells the story of Demon Maxwell. If Maxwell had been a nineteenth-century scientist, he would have posed a scientific problem in which a very small demon would be a companion in a doorway between two chambers large enough for a single molecule. The demon watched the molecules and chose which ones it let through the door.

Now I get to the heart of the matter. We designed the demon because our companion and scientists developed a hypothetical ancient demon in a knowna task where the demon’s activity was to observe the movement of molecules. Professor Corbato concludes his explanation of why

As you know, “system processes” called daemons undoubtedly take on other tasks and execute predefined parameters based on their behavior. This method resembles Maxwell’s demon fixing its molecules, so we can safely assume that whoever called “system processes” meant only Maxwell’s demon.

History also notes that Professor Salzzer, who also worked on the MAC project along with Professor Corbato, who used the “demon” in valuable time for this important purpose, confirms that this is “the origin of the demon, as it is also used in computing.

In multitasking computer operating systems, a special daemon ( or )^[1] is their computer program that runs as a last background process and is not under the direct control of an entertaining user. Traditionally, process names such asMost associated with a daemon end with the standard d to make it clear that the action is actually a daemon and also to distinguish a daemon from a regular computer program. For example, syslogd is the daemon that uses the system logging feature, while sshd is actually the daemon that handles incoming SSH connections.

In a Unix environment, a daemon’s guardian process is often, but not always, the act of initialization. A daemon is usually created by a process that calls a child process and then immediately kills it, causing init to take control of the child process, or an init entity that starts the daemon directly. This includes the fact that a daemon that was started by a fork but terminated should normally perform other functions, such as disassociating a process called by a controlling terminal (tty). Such surgical treatment is often implemented in various accessibility routines such as daemon(3) on Unix.

Systems often start daemons at boot time that respond to network applications, hardware activity, or otherprograms to perform a specific task. Daemons in the form of cron can also run given missions at set times.

Terminology

The term was developed by the programmers of the MAC project at the Massachusetts Institute of Technology. According to Fernando J. Corbato, who worked on the 1963 MAC project, his team was the first to use the term demon, inspired by Maxwell’s demon, an imaginary cause in physics and thermodynamics that helped sort molecules, and said: “We started creatively using a text messaging daemon to describe background processes that tirelessly performed system tasks.”^[2] Unix systems have inherited this terminology. on your own background.

In this sense, General Damon is an ancient fantasy form of the keyword “demon” from the Greek δαίμων. Evie Nemeth usually names the following daemons in the Unix System Administration Guide:^[3]

Many people usually equate the word “daemon” with the word “demon”, suggesting some kind of satanic connection between UNIX and a certain program.The underworld. This is outrageous disbelief. “Demon” is actually a slightly older form of the word “demon”; Demons do not have a particular propensity for good or evil, but rather serve to signify a person’s character or personality. The ancient Greek idea of ​​a fabulous “personal demon” is similar to today’s idea of ​​a “guardian angel” – eudaimonia is, of course, a state of assistance or, perhaps, protection of a benevolent spirit. Typically, UNIX systems help infecting both daemons and daemons.

Another characteristic of mythical symbolism is that the demon must be something that cannot be seen, but is always present and willful. In Theage, attributed to Plato, Socrates describes his personal demon as what I would call the modern conception of the moral sense: more prominent since he “comes out of childhood.” , prevents me from doing what I should be doing without even pushing me to do it.”^[quote]

In modern usage, the demon concept is pronounced DEE-mən. In the context of computers, the originalwear has been changed to help you use DAY-mən for some media.^[1]

Alternative time periods for the daemon: service (used by Windows, Windows NT, and later also Linux), running task (IBM z/OS), ^[4], and phantom job (XDSUTS). .

After the term “computer usage” became popular, the product was optimized as a backronym for Disk And Execution MONitor. ^[5]

Demons that connect to any computer network are examples of online circle services.

Implementation

Unix-like Systems

From a purely technical point of view, a Unix-like system process is indeed a daemon if its parent process terminates and the daemon once assigns a particular initialization process (process number 1) to its parent process and has little or no control terminal . . More generally, however, a daemon can be in the background at any time, whether or not it is a child of a new init process.

In a Unix-like human body, the usual way to becomea daemon is to run a path from the command line or from vbulletin start-zero, such as an init script or just a SystemStarter script:

Optional removal of environment variables that can be avoided.

Run as a base task by exiting and branching (to the parent “half” of the branch). This allows the parent daemon (a new enterprise or shell process) to receive an exit warning and continue normal execution.

Disconnect during a normal call session, essentially with a single setsid() operation:

Disable fine control of tty.A

Create a new session, taking over most of the session as the session leader.

Become a process group leader.

If most daemons want to be sure they don’t get a new controlling tty (causing a session leader without a controlling tty to open a completely free tty), it can always fork and terminate again. Does this mean it will never be the session leader in a new session and will not be able to get its own controlling terminal?

Installation Root (/) as the current directory prevents a process from using a directory that may be on a mounted file machine (and still cannot be mounted).