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: src/sbin/devd/devd.8,v 1.17 2006/09/17 22:49:26 ru Exp $ 27.\" $DragonFly: src/sbin/devd/devd.8,v 1.2 2008/10/03 10:30:43 swildner Exp $ 28.\" 29.Dd October 2, 2008 30.Dt DEVD 8 31.Os 32.Sh NAME 33.Nm devd 34.Nd "device state change daemon" 35.Sh SYNOPSIS 36.Nm 37.Op Fl Ddn 38.Op Fl f Ar file 39.Sh DESCRIPTION 40The 41.Nm 42daemon provides a way to have userland programs run when certain 43kernel events happen. 44.Pp 45The following options are accepted. 46.Bl -tag -width ".Fl f Ar file" 47.It Fl D 48Enable debugging messages. 49.It Fl d 50Run in the foreground instead of becoming a daemon. 51.It Fl f Ar file 52Use configuration file 53.Ar file 54instead of the default 55.Pa /etc/devd.conf . 56If option 57.Fl f 58is specified more than once, the last file specified is used. 59.It Fl n 60Do not process all pending events before becoming a daemon. 61Instead, call daemon right away. 62.El 63.Sh IMPLEMENTATION NOTES 64The 65.Nm 66utility 67is a system daemon that runs in the background all the time. 68Whenever a device is added to or removed from the device tree, 69.Nm 70will execute actions specified in 71.Xr devd.conf 5 . 72For example, 73.Nm 74might execute 75.Xr dhclient 8 76when an Ethernet adapter is added to the system, and kill the 77.Xr dhclient 8 78instance when the same adapter is removed. 79Another example would be for 80.Nm 81to use a table to locate and load via 82.Xr kldload 8 83the proper driver for an unrecognized device that is added to the system. 84.Pp 85The 86.Nm 87utility 88hooks into the 89.Xr devctl 4 90device driver. 91This device driver has hooks into the device configuration system. 92When nodes are added or deleted from the tree, this device will 93deliver information about the event to 94.Nm . 95Once 96.Nm 97has parsed the message, it will search its action list for that kind 98of event and perform the action with the highest matching value. 99For most mundane uses, the default handlers are adequate. 100However, for more advanced users, the power is present to tweak every 101aspect of what happens. 102.Pp 103The 104.Nm 105utility 106reads 107.Pa /etc/devd.conf 108or the alternate configuration file specified with a 109.Fl f 110option and uses that file to drive the rest of the process. 111While the format of this file is described in 112.Xr devd.conf 5 , 113some basics are covered here. 114In the 115.Ic options 116section, one can define multiple directories to search 117for config files. 118All files in these directories whose names match the pattern 119.Pa *.conf 120are parsed. 121These files are intended to be installed by third party vendors that 122wish to hook into the 123.Nm 124system without modifying the user's other 125config files. 126.Pp 127All messages that 128.Nm 129receives are forwarded to the 130.Ux 131domain socket at 132.Pa /var/run/devd.pipe . 133.Sh FILES 134.Bl -tag -width ".Pa /var/run/devd.pipe" -compact 135.It Pa /etc/devd.conf 136The default 137.Nm 138configuration file. 139.It Pa /var/run/devd.pipe 140The socket used by 141.Nm 142to communicate with its clients. 143.El 144.Sh SEE ALSO 145.Xr devctl 4 , 146.Xr devd.conf 5 147.Sh AUTHORS 148.An M. Warner Losh 149