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 270004 2014-08-14 22:33:56Z asomers $ 27.\" 28.Dd February 24, 2015 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 socket connections to 59.Ar num . 60The default connection limit is 10. 61.It Fl n 62Do not process all pending events before becoming a daemon. 63Instead, call daemon right away. 64.It Fl q 65Quiet mode. Only log messages at priority LOG_WARNING or above. 66.El 67.Sh IMPLEMENTATION NOTES 68The 69.Nm 70utility 71is a system daemon that runs in the background all the time. 72Whenever a device is added to or removed from the device tree, 73.Nm 74will execute actions specified in 75.Xr devd.conf 5 . 76For example, 77.Nm 78might execute 79.Xr dhclient 8 80when an Ethernet adapter is added to the system, and kill the 81.Xr dhclient 8 82instance when the same adapter is removed. 83Another example would be for 84.Nm 85to use a table to locate and load via 86.Xr kldload 8 87the proper driver for an unrecognized device that is added to the system. 88.Pp 89The 90.Nm 91utility 92hooks into the 93.Xr devctl 4 94device driver. 95This device driver has hooks into the device configuration system. 96When nodes are added or deleted from the tree, this device will 97deliver information about the event to 98.Nm . 99Once 100.Nm 101has parsed the message, it will search its action list for that kind 102of event and perform the action with the highest matching value. 103For most mundane uses, the default handlers are adequate. 104However, for more advanced users, the power is present to tweak every 105aspect of what happens. 106.Pp 107The 108.Nm 109utility 110reads 111.Pa /etc/devd.conf 112or the alternate configuration file specified with a 113.Fl f 114option and uses that file to drive the rest of the process. 115While the format of this file is described in 116.Xr devd.conf 5 , 117some basics are covered here. 118In the 119.Ic options 120section, one can define multiple directories to search 121for config files. 122All files in these directories whose names match the pattern 123.Pa *.conf 124are parsed. 125These files are intended to be installed by third party vendors that 126wish to hook into the 127.Nm 128system without modifying the user's other 129config files. 130.Pp 131Since 132.Xr devctl 4 133allows only one active reader, 134.Nm 135multiplexes it, forwarding all events to any number of connected clients. 136Clients connect by opening the SOCK_SEQPACKET 137.Ux 138domain socket at 139.Pa /var/run/devd.seqpacket.pipe . 140.Sh FILES 141.Bl -tag -width ".Pa /var/run/devd.seqpacket.pipe" -compact 142.It Pa /etc/devd.conf 143The default 144.Nm 145configuration file. 146.It Pa /var/run/devd.seqpacket.pipe 147The socket used by 148.Nm 149to communicate with its clients. 150.It Pa /var/run/devd.pipe 151A deprecated socket retained for use with old clients. 152.El 153.Sh SEE ALSO 154.Xr devctl 4 , 155.Xr devd.conf 5 156.Sh AUTHORS 157.An M. Warner Losh 158