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22 lines
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<?xml version="1.0" encoding="ISO-8859-1" standalone="no"?>
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<html xmlns="http://www.w3.org/1999/xhtml"><head><title>daemon</title><link rel="stylesheet" href="../../jargon.css" type="text/css"/><meta name="generator" content="DocBook XSL Stylesheets V1.61.0"/><link rel="home" href="../index.html" title="The Jargon File"/><link rel="up" href="../D.html" title="D"/><link rel="previous" href="../D.html" title="D"/><link rel="next" href="daemon-book.html" title="daemon book"/></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">daemon</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="../D.html">Prev</a><EFBFBD></td><th width="60%" align="center">D</th><td width="20%" align="right"><EFBFBD><a accesskey="n" href="daemon-book.html">Next</a></td></tr></table><hr/></div><dt><a id="daemon"/><dt xmlns="" id="daemon"><b>daemon</b>: <span xmlns="http://www.w3.org/1999/xhtml" class="pronunciation">/day<61>mn/</span>, <span xmlns="http://www.w3.org/1999/xhtml" class="pronunciation">/dee<65>mn/</span>, <span xmlns="http://www.w3.org/1999/xhtml" class="grammar">n.</span></dt></dt><dd><p> [from Maxwell's Demon, later incorrectly retronymed as ‘Disk
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And Execution MONitor’] A program that is not invoked explicitly, but
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lies dormant waiting for some condition(s) to occur. The idea is that the
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perpetrator of the condition need not be aware that a daemon is lurking
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(though often a program will commit an action only because it knows that it
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will implicitly invoke a daemon). For example, under
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<a href="../I/ITS.html"><i class="glossterm">ITS</i></a>, writing a file on the LPT spooler's directory
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would invoke the spooling daemon, which would then print the file. The
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advantage is that programs wanting (in this example) files printed need
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neither compete for access to nor understand any idiosyncrasies of the LPT.
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They simply enter their implicit requests and let the daemon decide what to
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do with them. Daemons are usually spawned automatically by the system, and
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may either live forever or be regenerated at intervals.</p></dd><dd><p>Daemon and <a href="demon.html"><i class="glossterm">demon</i></a> are often used
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interchangeably, but seem to have distinct connotations. The term
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<span class="firstterm">daemon</span> was introduced to computing by
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<a href="../C/CTSS.html"><i class="glossterm">CTSS</i></a> people (who pronounced it <span class="pronunciation">/dee<65>mon/</span>) and used it to refer to
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what ITS called a <a href="dragon.html"><i class="glossterm">dragon</i></a>; the prototype was a
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program called DAEMON that automatically made tape backups of the file
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system. Although the meaning and the pronunciation have drifted, we think
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this glossary reflects current (2003) usage.</p></dd><div class="navfooter"><hr/><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="../D.html">Prev</a><EFBFBD></td><td width="20%" align="center"><a accesskey="u" href="../D.html">Up</a></td><td width="40%" align="right"><EFBFBD><a accesskey="n" href="daemon-book.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">D<EFBFBD></td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"><EFBFBD>daemon book</td></tr></table></div></body></html>
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