alicia@bucsb.bu.edu.UUCP (01/31/87)
Hey out there, it's late and we're tired... but we have a
question. Why are daemons (like,"rwhod", "talkd", "rsendd"...)
called "daemons". I mean, we know it's Latin for something that's
not quite a God, but more than a man - but how does that relate.
My first association is that daemons are eternal... but I
don't know.... just curios....
alicia
jsq@im4u.UUCP (02/03/87)
In article <711@bucsb.bu.edu.UUCP> alicia@bucsb.bu.edu.UUCP (alicia h) writes: > > Hey out there, it's late and we're tired... but we have a > question. Why are daemons (like,"rwhod", "talkd", "rsendd"...) > called "daemons". I mean, we know it's Latin for something that's > not quite a God, but more than a man - but how does that relate. > My first association is that daemons are eternal... but I > don't know.... just curios.... > > > alicia The following definition comes from the jargon file, long maintained in the distant past (more than five years ago) on several ARPANET machines. An updated version appeared in print in the near past as The Hacker's Dictionary, which you should run out and buy a copy of (I have no connection, financial or otherwise, with the book); it being a curio like yourself, no doubt you'll like it. :-) DAEMON (day'mun, dee'mun) [archaic form of "demon", which has slightly different connotations (q.v.)] n. A program which is not invoked explicitly, but which lays 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, writing a file on the lpt spooler's directory will invoke the spooling daemon, which prints the file. The advantage is that programs which want (in this example) files printed need not compete for access to 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. Usage: DAEMON and DEMON (q.v.) are often used interchangeably, but seem to have distinct connotations. DAEMON was introduced to computing by CTSS people (who pronounced it dee'mon) and used it to refer to what is now called a DRAGON or PHANTOM (q.v.). The meaning and pronunciation have drifted, and we think this glossary reflects current usage. -- John Quarterman, UUCP: {gatech,harvard,ihnp4,pyramid,seismo}!ut-sally!im4u!jsq ARPA Internet and CSNET: jsq@im4u.UTEXAS.EDU, jsq@sally.UTEXAS.EDU
budd@bu-cs.UUCP (02/03/87)
The name daemon has long been used in the PDP-10 (36 bit) world, TOPS-10 has the DAEMON job that historically served user requests to create core dumps, very long term sleep wakeups, acounting file, and system error log entries. DAEMON communicated with the monitor by a SPY segment, that is instead of a pure text segment it had a read only mapping of the monitor, and returned data via a special call. Daemon is sometimes spelled deamon. Another term for daemon is dragon, ITS has PFTMGD "Puff the Magic Dragon" that does magic things (like at/cron) Un*x has long had 'lpd', and while TOPS-10 was born a decade before Un*x I'm unsure when the DAEMON appeared? Anyone prepared to kindle my hair on all this? Phil Budne Boston University Distributed Systems Group of Distributed Computing and Communications section of DisInformation Technology
tony@catsim.UUCP (02/03/87)
In article <711@bucsb.bu.edu.UUCP>, alicia@bucsb.bu.edu.UUCP (alicia h) writes: > > Hey out there, it's late and we're tired... but we have a > question. Why are daemons (like,"rwhod", "talkd", "rsendd"...) > called "daemons". I mean, we know it's Latin for something that's > not quite a God, but more than a man - but how does that relate. > My first association is that daemons are eternal... but I > don't know.... just curios.... > > > alicia > If you have a copy of the "HACKER'S DICTIONARY" the answer lies on page 53. Here is a part of the definition: { A program that is not invoked explicitly, but that lies dormant waiting for one or more conditions to occure. 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). . . . Daemon and DEMON are often used interchangeably, but seem to have discrete connotations. "Daemon" was introduced to computing by people working on CTSS, the Compatible Time-Sharing System, which was the first time-sharing system, developed atMIT. The pronounced it "dee'm:o," and used it to refer to what is now call a DRAGON or PHANTOM. THe meaning an pronunciation have drifed, and we think the definitions given here reflect current usage. } If you don't have a copy of Hacker's Dictionary I would suggest that you try to find one. Tony Cratz UUCP: hplabs!intelca!catsim!tony Mail: 4051 Burton Dr. Santa Clara, Ca. 95054 Phone: 408-980-9144
tim@hoptoad.UUCP (02/04/87)
A "demon" (as opposed to "daemon") is a bug that vanishes when you run your
software under the debugger, but remains otherwise.
--
Tim Maroney, Electronic Village Idiot
{ihnp4,sun,well,ptsfa,lll-crg,frog}!hoptoad!tim (uucp)
hoptoad!tim@lll-crg (arpa)
Second Coming Still Vaporware After 2,000 Yearsbzs@bu-cs.UUCP (02/04/87)
I believe the image of a software 'daemon' came from AI lingo for a piece of code which waited in the shadows and awoke when it was needed. I know the term is used like that in older AI literature to describe a form of event-driven programming where the system was designed as a "panel" of experts or daemons each waiting for a question in his/her/its field to arrive at which time it would pop up, answer it, and then disappear again back into the shadows. I suspect the sum of its metaphysical+AI implications (not to mention being a perfect metaphor if you accept the above) made it irresistible to us system types as a term for such programs. Or, perhaps the account just appeared on the system one day when one not ready typed in the true name of root... -Barry Shein, Boston University [Obviously I am just trying to relate it to its software usage, a good dictionary should reveal its common usage.]
chapman@eris.UUCP (02/04/87)
In article <1729@hoptoad.uucp> tim@hoptoad.UUCP (Tim Maroney) writes: >A "demon" (as opposed to "daemon") is a bug that vanishes when you run your >software under the debugger, but remains otherwise. No, that's a Heisenbug... :-) Brent -- Brent Chapman chapman@eris.berkeley.edu or ucbvax!eris!chapman
edm@tikal.UUCP (02/17/87)
As I understand it, "demons" were "bad" spirits and "daemons" were "good"
ones. So I guess the idea is that all those "daemons" running in the back-
ground on UNIX are supposed to be good because they help you in some way
while using the system...
--
Ed Morin - Teltone Corporation
...uw-beaver_____!tikal!edm 10801 - 120th Ave. N.E.
.......fluke___/ Kirkland, WA 98033
(206) 827-9626