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 50The 51.Nm 52utility 53is a system daemon that runs in the background all the time. 54Whenever a device is added to or removed from the device tree, 55.Nm 56will execute actions specified in 57.Xr devd.conf 5 . 58For example, 59.Nm 60might execute 61.Xr dhclient 8 62when an Ethernet adapter is added to the system, and kill the 63.Xr dhclient 8 64instance when the same adapter is removed. 65Another example would be for 66.Nm 67to use a table to locate and load via 68.Xr kldload 8 69the proper driver for an unrecognized device that is added to the system. 70.Pp 71The 72.Nm 73utility 74hooks into the 75.Xr devctl 4 76device driver. 77This device driver has hooks into the device configuration system. 78When nodes are added or deleted from the tree, this device will 79deliver information about the event to 80.Nm . 81Once 82.Nm 83has parsed the message, it will search its action list for that kind 84of event and perform the action with the highest matching value. 85For most mundane uses, the default handlers are adequate. 86However, for more advanced users, the power is present to tweak every 87aspect of what happens. 88.Pp 89The 90.Nm 91utility 92reads 93.Pa /etc/devd.conf 94and uses that file to drive the rest of the process. 95While the format of this file is described in 96.Xr devd.conf 5 , 97some basics are covered here. 98In the 99.Ic options 100section, one can define multiple directories to search 101for config files. 102All files in each of these directories are parsed. 103These files are intended to be installed by third party vendors that 104wish to hook into the 105.Nm 106system without modifying the user's other 107config files. 108.Sh SEE ALSO 109.Xr devctl 4 , 110.Xr devd.conf 5 111.Sh AUTHORS 112.An M. Warner Losh 113