Kernel Hotplug Helper (/sbin/hotplug) There is a kernel parameter: /proc/sys/kernel/hotplug, which normally holds the pathname /sbin/hotplug. That parameter names a program which the kernel may invoke at various times.
The /sbin/hotplug program can be invoked by any subsystem as part of its reaction to a configuration change, from a thread in that subsystem. Only one parameter is required: the name of a subsystem being notified of some kernel event. That name is used as the first key for further event dispatch; any other argument and environment parameters are specified by the subsystem making that invocation.
Hotplug software and other resources is available at:
http://linux-hotplug.sourceforge.net Mailing list information is also available at that site.