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DEVD(8)                 FreeBSD System Manager's Manual                DEVD(8)

     devd - device state change daemon

     devd [-Ddn]

     The devd daemon provides a way to have userland programs run when certain
     kernel events happen.

     The following options are accepted.

     -D      Enable debugging messages.

     -d      Run in the foreground instead of becoming a daemon.

     -n      Do not process all pending events before becoming a daemon.
             Instead, call daemon right away.

     The devd 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,
     devd will execute actions specified in devd.conf(5).  For example, devd
     might execute dhclient(8) when an Ethernet adapter is added to the
     system, and kill the dhclient(8) instance when the same adapter is
     removed.  Another example would be for devd to use a table to locate and
     load via kldload(8) the proper driver for an unrecognized device that is
     added to the system.

     The devd utility hooks into the 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 devd.  Once devd 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.

     The devd utility reads /etc/devd.conf and uses that file to drive the
     rest of the process.  While the format of this file is described in
     devd.conf(5), some basics are covered here.  In the 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 devd system
     without modifying the user's other config files.

     devctl(4), devd.conf(5)

     M. Warner Losh

FreeBSD 11.0-PRERELEASE        October 17, 2002        FreeBSD 11.0-PRERELEASE


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