Talk:Daemon (computer software)

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 Definition a computer program that runs by itself, as opposed to being directly controlled by a user or another program. [d] [e]
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Controlled by another program?

The original UNIX definition was that a daemon had no associated tty, but I'd hesitate to say that it isn't controlled by another program -- to me, the program that spawns it exerts control. It should be sufficient to say it has no user. Howard C. Berkowitz 20:11, 1 October 2009 (UTC)

Good point. I was thinking of daemons that respond only to events, but of course programs can generate those events also. A daemon is controlled by its parent, even if that control is only to terminate the daemon.
Webopedia uses the concept of "background process", meaning "not controlled by the user". I'll delete "or another program".
--David MacQuigg 20:38, 1 October 2009 (UTC)

Pat, I think the latest edits are incorrect, and we should revert to the previous wording until we have more time to discuss.
1) "A daemon is a computer program that runs automatically when a computer boots up, as opposed to being directly started by a user."
Daemons can be started either way, and many are started (and restarted) by some user action. Sendmail, for example, runs as a daemon. I restart it every time I make a configuration change. Same for the mail filter and the spam-blocking process, firewalls, etc.
2) "doing everything from scheduling tasks to"
If we make a distinction between the old wording "running scheduled tasks" and the new wording "scheduling tasks", then the former is more common. I am thinking of the cron daemon. The user sets up whatever schedule is to be followed. Thereafter, the daemon runs the designated tasks, following the schedule set up by the user. I don't know of any daemons that actually schedule the tasks themselves, although nothing would prevent that. The cron schedule is just a text file.
3) "Daemons, or services, run in the background"
I don't think this is always true, but perhaps we could ask someone more experienced in Unix systems. The background/foreground issue has more to do with priority of tasks. User-controlled processes usually need priority over daemons, but I can imagine a daemon running in the foreground if it needs a higher priority.
4) "Daemon is the term used in Unix"
This is a minor issue, more a matter of style than correctness, but I do think some readers, particularly those that are familiar only with Windows, will wonder about the origin of Unix terms like daemon, the archaic spelling, etc. It might be re-assuring to let them know this is just a bit of geek humor, not some fundamental concept they are missing.
--David MacQuigg 15:47, 22 February 2010 (UTC)