Copyright (c) 2002 M. Warner Losh.
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$FreeBSD: head/sbin/devd/devd.8 115114 2003-05-17 22:21:27Z ru $

.Dd October 17, 2002 .Dt DEVD 8 .Os .Sh NAME .Nm devd .Nd "device state change daemon" .Sh SYNOPSIS .Nm .Op Fl Ddn .Sh DESCRIPTION The .Nm daemon provides a way to have userland programs run when certain kernel events happen.

p The following options are accepted. l -tag -width indent t Fl D Enable debugging messages. t Fl d Run in the foreground instead of becoming a daemon. t Fl n Do not process all pending events before becoming a daemon. Instaed, call daemon right away. .El .Sh IMPLEMENTATION NOTES The .Nm utility is a system daemon that runs in the background all the time. Whenever a device is added to or removed from the device tree, .Nm will execute actions specified in .Xr devd.conf 5 . For example, .Nm might execute .Xr dhclient 8 when an Ethernet adapter is added to the system, and kill the .Xr dhclient 8 instance when the same adapter is removed. Another example would be for .Nm to use a table to locate and load via .Xr kldload 8 the proper driver for an unrecognized device that is added to the system.

p The .Nm utility hooks into the .Xr devctl 4 device driver. This device driver has hooks into the device configuration system. When nodes are added or deleted from the tree, this device will deliver information about the event to .Nm . Once .Nm has parsed the message, it will search its action list for that kind of event and perform the action with the highest matching value. For most mundane uses, the default handlers are adequate. However, for more advanced users, the power is present to tweak every aspect of what happens.

p The .Nm utility reads

a /etc/devd.conf and uses that file to drive the rest of the process. While the format of this file is described in .Xr devd.conf 5 , some basics are covered here. In the c options section, one can define multiple directories to search for config files. All files in each of these directories are parsed. These files are intended to be installed by third party vendors that wish to hook into the .Nm system without modifying the user's other config files. .Sh SEE ALSO .Xr devctl 4 , .Xr devd.conf 5 .Sh AUTHORS .An M. Warner Losh