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

     devd -- Device state change daemon

     devd [-d]

     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 and run in the foreground instead of
	     becoming a	daemon.

     devd is a system daemon that runs in the background all the time.	When-
     ever a device is added to or removed from the device tree,	devd will exe-
     cute actions specified in devd.conf(5).  For example, devd	might execute
     dhclient(8) when an ethernet adapter is added to the system 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.

     devd 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 ac-
     tion list for that	kind of	event and perform the action with the highest
     matching value.  For most mundane uses, the default handlers are ade-
     quate.  However, for more advanced	users, the power is present to tweak
     every aspect of what happens.

     devd 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 di-
     rectories 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.

     devctl(4),	devd.conf(5)

     M.	Warner Losh

     devd currently always runs	"/etc/devd-generic $device $startstop" for all
     device events, regardless of what the config file says to do.

BSD			       October 17, 2002				   BSD


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