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: head/sbin/devd/devd.8 262914 2014-03-07 23:30:48Z asomers $ 27.\" 28.Dd January 30, 2013 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 dnq 37.Op Fl f Ar file 38.Op Fl l Ar num 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 48Run in the foreground instead of becoming a daemon and log additional information for debugging. 49.It Fl f Ar file 50Use configuration file 51.Ar file 52instead of the default 53.Pa /etc/devd.conf . 54If option 55.Fl f 56is specified more than once, the last file specified is used. 57.It Fl l Ar num 58Limit concurrent 59.Pa /var/run/devd.pipe 60connections to 61.Ar num . 62The default connection limit is 10. 63.It Fl n 64Do not process all pending events before becoming a daemon. 65Instead, call daemon right away. 66.It Fl q 67Quiet mode. Only log messages at priority LOG_WARNING or above. 68.El 69.Sh IMPLEMENTATION NOTES 70The 71.Nm 72utility 73is a system daemon that runs in the background all the time. 74Whenever a device is added to or removed from the device tree, 75.Nm 76will execute actions specified in 77.Xr devd.conf 5 . 78For example, 79.Nm 80might execute 81.Xr dhclient 8 82when an Ethernet adapter is added to the system, and kill the 83.Xr dhclient 8 84instance when the same adapter is removed. 85Another example would be for 86.Nm 87to use a table to locate and load via 88.Xr kldload 8 89the proper driver for an unrecognized device that is added to the system. 90.Pp 91The 92.Nm 93utility 94hooks into the 95.Xr devctl 4 96device driver. 97This device driver has hooks into the device configuration system. 98When nodes are added or deleted from the tree, this device will 99deliver information about the event to 100.Nm . 101Once 102.Nm 103has parsed the message, it will search its action list for that kind 104of event and perform the action with the highest matching value. 105For most mundane uses, the default handlers are adequate. 106However, for more advanced users, the power is present to tweak every 107aspect of what happens. 108.Pp 109The 110.Nm 111utility 112reads 113.Pa /etc/devd.conf 114or the alternate configuration file specified with a 115.Fl f 116option and uses that file to drive the rest of the process. 117While the format of this file is described in 118.Xr devd.conf 5 , 119some basics are covered here. 120In the 121.Ic options 122section, one can define multiple directories to search 123for config files. 124All files in these directories whose names match the pattern 125.Pa *.conf 126are parsed. 127These files are intended to be installed by third party vendors that 128wish to hook into the 129.Nm 130system without modifying the user's other 131config files. 132.Pp 133All messages that 134.Nm 135receives are forwarded to the 136.Ux 137domain socket at 138.Pa /var/run/devd.pipe . 139.Sh FILES 140.Bl -tag -width ".Pa /var/run/devd.pipe" -compact 141.It Pa /etc/devd.conf 142The default 143.Nm 144configuration file. 145.It Pa /var/run/devd.pipe 146The socket used by 147.Nm 148to communicate with its clients. 149.El 150.Sh SEE ALSO 151.Xr devctl 4 , 152.Xr devd.conf 5 153.Sh AUTHORS 154.An M. Warner Losh 155