Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages


home | help
DEVD(8)			  BSD System Manager's Manual		       DEVD(8)

     devd -- device state change daemon

     devd [-Ddn] [-f file] [-l num]

     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.

     -f	file  Use configuration	file file instead of the default
	      /etc/devd.conf.  If option -f is specified more than once, the
	      last file	specified is used.

     -l	num   Limit concurrent /var/run/devd.pipe connections to num.  The de-
	      fault connection limit is	10.

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

     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 or the alternate configuration file
     specified with a -f option	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 these di-
     rectories whose names match the pattern *.conf 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.

     All messages that devd receives are forwarded to the UNIX domain socket
     at	/var/run/devd.pipe.

     /etc/devd.conf	 The default devd configuration	file.
     /var/run/devd.pipe	 The socket used by devd to communicate	with its

     devctl(4),	devd.conf(5)

     M.	Warner Losh

BSD			       January 30, 2013				   BSD


Want to link to this manual page? Use this URL:

home | help