Ubuntu: run a script when a USB device is plugged in

There's a lot of stuff you can do with udev. One of them is running a script when a USB device is plugged in.

It's as simple as:

1. figure out the vendor id and product id with lsusb
2. edit /etc/udev/rules.d/85-something.rules:

ACTION=="add", SUBSYSTEM=="usb", ATTR{idVendor}=="04c5", ATTR{idProduct}=="11a2", RUN+="/absolute/path/to/your/script/that/will/be/executed/as/root"

3. Write the script mentioned above and make sure it's executable.
4. Restart udev: service udev restart.

You can do other things with udev such as managing /dev/ and the permissions on the device.
However you should not use udev to mount USB disks, there are other tools for that.

To run a script when detaching a USB device, replace ACTION=="add" with ACTION=="remove". You can put several lines in the same ".rules" file.