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## Auto-converted by kwiki2moinmoin v2005-10-07
Pronunciation:{{{
 day'mn or dee'mn
#language en
~-[[DebianWiki/EditorGuide#translation|Translation(s)]]: English-~
----
A [[http://en.wikipedia.org/wiki/Daemon_(computing)|daemon]], or service, is a background process usually started during the initial boot sequence by [[init]]. Daemons typically run independent of users, waiting for events to occur and providing services. Some common daemons include:

 * sshd - listens for and manages incoming [[SSH]] connections
 * [[acpid]] - listens for power management events and triggers scripts based on them)
 * [[Apache|apache]] - provides a local HTTP web server

## If your page gets really long, uncomment this Table of Contents
## <<TableOfContents(2)>>

== Daemons under Debian ==
Debian makes use of [[http://en.wikipedia.org/wiki/Init#SysV-style|System V]]-style init scripts for daemon management, allowing daemons to run conditionally, based on the current RunLevel of the computer. For example, a daemon can be configured to run only when the computer is in single-user mode (runlevel 1) or, more commonly, when in multi-user mode (runlevels 2-5). For more information, see RunLevel.
 
== Debian daemon configuration ==
''Note: Many daemons provide essential services to a working Debian installation; others can pose as unnecessary security risks when enabled. Caution should be used whenever managing daemons. When in doubt, refer to the documentation of the daemon itself.''
 
=== Start, stop and reload daemons ===
The easiest way to manually (and temporarily) start, stop or reload a daemon is to run the following in a terminal as root:
{{{
# /etc/init.d/daemonname [stop|start|restart]
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Controlling daemons in this manner is temporary and will not survive a reboot. Refer to the next section to manage daemons on a more permanent basis.
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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. From Jargon Dictionary http://www.tldp.org/LDP/Linux-Dictionary/html/index.html

A background process of the operating system that usually has root security level permission. A daemon usually lurks in the background until something triggers it into activity, such as a specific time or date, time interval, receipt of e-mail, etc. From I-gloss http://www.tldp.org/LDP/Linux-Dictionary/html/index.html

A process lurking in the background, usually unnoticed, until something triggers it into action. For example, the \cmd{update} daemon wakes up every thirty seconds or so to flush the buffer cache, and the \cmd{sendmail} daemon awakes whenever someone sends mail. http://www.tldp.org/LDP/Linux-Dictionary/html/index.html

A program that runs continuously in the background, until activated by a particular event. A daemon can constantly query for requests or await direct action from a user or other process. From Redhat-9-Glossary http://www.tldp.org/LDP/Linux-Dictionary/html/index.html
=== Enable/disable daemons ===
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A program which runs for an extended period (usually "forever") to handle requests for service as needed. From Linux Guide @FirstLinux http://www.tldp.org/LDP/Linux-Dictionary/html/index.html == See also ==
 * [[init]]
 * [[RunLevel]]
 * manpages: [[DebianMan:5/inittab|inittab]],[[DebianMan:8/init|init]],[[DebianMan:5/rcS|rcS]], [[DebianMan:8/update-rc.d|update-rc.d]], [[DebianMan:8/runlevel|runlevel]]
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A program, usually on a computer running UNIX, that serves some obscure function (such as routing electronic mail to its recipients) and usually has a very limited user interface. There's some debate about the origins of the word, but most say it derives from the devilish spirits of Greek mythology. From QUECID http://www.tldp.org/LDP/Linux-Dictionary/html/index.html

Disk And Execution ["MONitor"] (Unix) From VERA http://www.tldp.org/LDP/Linux-Dictionary/html/index.html

Daemon (service)
On ["UNIX"], a daemon is a program running in the background, usually providing some sort of service. Typical daemons are those that provide e-mail, printing, telnet, FTP, and web access. From Hacking-Lexicon http://www.tldp.org/LDP/Linux-Dictionary/html/index.html
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## CategorySomething | CategoryAnother

Translation(s): English


A daemon, or service, is a background process usually started during the initial boot sequence by ?init. Daemons typically run independent of users, waiting for events to occur and providing services. Some common daemons include:

  • sshd - listens for and manages incoming SSH connections

  • acpid - listens for power management events and triggers scripts based on them)

  • apache - provides a local HTTP web server

Daemons under Debian

Debian makes use of System V-style init scripts for daemon management, allowing daemons to run conditionally, based on the current RunLevel of the computer. For example, a daemon can be configured to run only when the computer is in single-user mode (runlevel 1) or, more commonly, when in multi-user mode (runlevels 2-5). For more information, see RunLevel.

Debian daemon configuration

Note: Many daemons provide essential services to a working Debian installation; others can pose as unnecessary security risks when enabled. Caution should be used whenever managing daemons. When in doubt, refer to the documentation of the daemon itself.

Start, stop and reload daemons

The easiest way to manually (and temporarily) start, stop or reload a daemon is to run the following in a terminal as root:

# /etc/init.d/daemonname [stop|start|restart]

Controlling daemons in this manner is temporary and will not survive a reboot. Refer to the next section to manage daemons on a more permanent basis.

Enable/disable daemons

See also