daemon /day'mn/ or /dee'mn/ n.
[from the mythological meaning, later rationalized as the acronym `Disk And Execution MONitor'] A program that is not invoked explicitly, but lies dormant waiting for some condition(s) to occur. The idea is that the perpetrator of the condition need not be aware that a daemon is lurking (though often a program will commit an action only because it knows that it will implicitly invoke a daemon). For example, under ITS writing a file on the LPT spooler's directory would invoke the spooling daemon, which would then print the file. The advantage is that programs wanting (in this example) files printed need neither compete for access to nor understand any idiosyncrasies of the LPT. They simply enter their implicit requests and let the daemon decide what to do with them. Daemons are usually spawned automatically by the system, and may either live forever or be regenerated at intervals.
Daemon and demon are often used interchangeably, but seem to have distinct connotations. The term `daemon' was introduced to computing by CTSS people (who pronounced it /dee'mon/) and used it to refer to what ITS called a dragon; the prototype was a program called DAEMON that automatically made tape backups of the file system. Although the meaning and the pronunciation have drifted, we think this glossary reflects current (2000) usage.
daemon book n.
"The Design and Implementation of the 4.3BSD UNIX Operating System", by Samuel J. Leffler, Marshall Kirk McKusick, Michael J. Karels, and John S. Quarterman (Addison-Wesley Publishers, 1989, ISBN 0-201-06196-1); or "The Design and Implementation of the 4.4 BSD Operating System" by Marshall Kirk McKusick, Keith Bostic, Michael J. Karels and John S. Quarterman (Addison-Wesley Longman, 1996, SBN 0-201-54979-4) Either of the standard reference books on the internals of BSD Unix. So called because the covers have a picture depicting a little devil (a visual play on daemon) in sneakers, holding a pitchfork (referring to one of the characteristic features of Unix, the fork(2) system call). Also known as the Devil Book.
But also.......
Main Entry: de·mon
Variant(s): or dae·mon /'dE-m&n/
Function: noun
Etymology: Middle English demon, from Late Latin & Latin; Late Latin daemon evil spirit, from Latin, divinity, spirit, from Greek daimOn, probably from daiesthai to distribute -- more at TIDE
1 a : an evil spirit b : a source or agent of evil, harm, distress, or ruin
2 usually daemon : an attendant power or spirit : GENIUS
3 usually daemon : a supernatural being of Greek mythology intermediate between gods and men
4 : one that has exceptional enthusiasm, drive, or effectiveness <a demon for work>
- de·mo·ni·an /di-'mO-nE-&n/ adjective
- de·mon·iza·tion /"dE-m&-n&-'zA-sh&n/ noun
- de·mon·ize /'dE-m&-"nIz/ transitive verb