How can I get real-time information about monitor plug/unplug events?

When I connect or disconnect the USB device, udev shows/monitors that event. But udev is not enough smart to detect the plug-out or plug-in of the monitor. Is there any way/tool/utility from which I will get real-time information about the plug-out or plug-in of a monitor? (I know how to get [EDID information](https://unix.stackexchange.com/questions/7622/edid-information) at some point in time, but not how to react when a monitor is plugged in.)