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DEVD(8)			FreeBSD	System Manager's Manual		       DEVD(8)

NAME
     devd -- device state change daemon

SYNOPSIS
     devd [-Ddn]

DESCRIPTION
     The devd daemon provides a	way to have userland programs run when certain
     kernel events happen.

     The following options are accepted.

     -D	     Enable debugging messages.

     -d	     Run in the	foreground instead of becoming a daemon.

     -n	     Do	not process all	pending	events before becoming a daemon.
	     Instead, call daemon right	away.

IMPLEMENTATION NOTES
     The devd utility is a system daemon that runs in the background all the
     time.  Whenever a device is added to or removed from the device tree,
     devd will execute actions specified in devd.conf(5).  For example,	devd
     might execute dhclient(8) when an Ethernet	adapter	is added to the	sys-
     tem, and kill the dhclient(8) instance when the same adapter is removed.
     Another example would be for devd to use a	table to locate	and load via
     kldload(8)	the proper driver for an unrecognized device that is added to
     the system.

     The devd utility hooks into the devctl(4) device driver.  This device
     driver has	hooks into the device configuration system.  When nodes	are
     added or deleted from the tree, this device will deliver information
     about the event to	devd.  Once devd has parsed the	message, it will
     search its	action list for	that kind of event and perform the action with
     the highest matching value.  For most mundane uses, the default handlers
     are adequate.  However, for more advanced users, the power	is present to
     tweak every aspect	of what	happens.

     The devd utility reads /etc/devd.conf and uses that file to drive the
     rest of the process.  While the format of this file is described in
     devd.conf(5), some	basics are covered here.  In the options section, one
     can define	multiple directories to	search for config files.  All files in
     each of these directories are parsed.  These files	are intended to	be
     installed by third	party vendors that wish	to hook	into the devd system
     without modifying the user's other	config files.

SEE ALSO
     devctl(4),	devd.conf(5)

AUTHORS
     M.	Warner Losh

FreeBSD	10.1		       October 17, 2002			  FreeBSD 10.1

NAME | SYNOPSIS | DESCRIPTION | IMPLEMENTATION NOTES | SEE ALSO | AUTHORS

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