I found out that user space scripts in /etc/hotplug/usb don't get executed if there is already an entry with same vendor/device-id in /lib/modules/2.4.18-686-1/modules.usbmap. I don't want to delete that entry. I only want the camera module in blacklist (this works) and a script beeing executed according to usb.usermap (this works not). Is this a bug or can I control where hotplug looks first what to do?