1.\" 2.\" Copyright (c) 2002 M. Warner Losh. 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24.\" SUCH DAMAGE. 25.\" 26.\" $FreeBSD$ 27.\" 28.Dd October 17, 2002 29.Dt DEVD 8 30.Os 31.Sh NAME 32.Nm devd 33.Nd "Device state change daemon" 34.Sh SYNOPSIS 35.Nm 36.Op Fl d 37.Sh DESCRIPTION 38The 39.Nm 40daemon provides a way to have userland programs run when certain 41kernel events happen. 42.Pp 43The following options are accepted. 44.Bl -tag -width indent 45.It Fl d 46Enable debugging messages and run in the foreground instead of 47becoming a daemon. 48.El 49.Sh IMPLEMENTATION NOTES 50.Nm 51is a system daemon. 52It runs in the background all the time. 53When ever a device is added to or removed from the device tree, devd 54will cause a certain action to take place. 55In addition, when a device that is not matched enters the system, devd 56will also perform an action. 57.Pp 58.Nm 59hooks into the 60.Xr devctl 4 61device driver. 62This device driver has hooks into the device configuration system. 63When nodes are added or deleted from the tree, this device will 64deliver information about the even to 65.Nm . 66Once 67.Nm 68has parsed the message, it will search its action list for that kind 69of event, and perform the action with the highest matching value. 70For most mundane uses, the default handlers are adequate. 71However, for more advanced users, the power is present to tweak every 72aspect of what happens. 73.Pp 74.Nm reads /etc/devd.conf, and that drives the rest of the process. 75While the format of this file is described in 76.Xr devd.conf 5 77some basics are covered here. 78In the options section, one can define multiple directories to search 79for config files. 80All files in each of these directories are parsed. 81These files are intended to be installed by third party vendors that 82wish to hook into the devd system without modifying the user's other 83config files. 84.Sh SEE ALSO 85.Xr devctl 4 , 86.Xr devd.conf 5 87.Sh AUTHORS 88.An M. Warner Losh 89