linux – How to Be Notified When USB Device is Plugged In

It is sometimes possible to do a power cycle on branch of the USB bus where the device is plugged :

# echo suspend > /sys/bus/usb/devices/1-1/power/level
# echo auto > /sys/bus/usb/devices/1-1/power/level

The 1-1 should be adjusted to your configuration. You can see to which part of the USB tree your device is plugged by running lsusb -t before ejecting it.

You can find detailed information on the linux-usb mailing-list, this thread for example.

Your problem would be solved if both the Pi and the powered storage device were on a UPS.

This is a common problem with /media. It will take the assigned name and begin adding digits if it hasn't cleared its cache (usually requires a reboot) before you unplug then replug (or unpower then repower the storage device).

Conversely, one thing always remains constant: The USB connection to the (first) Arduino Nano is always named /dev/ttyUSB0 and the (first) USB connection to an Arduino Uno is /dev/ttyACM0 -- They just disappear when it is unplugged then come right back when replugged.

The only way to confuse them is if you have more than one of the same type (Nano or Uno) and you replug them in a different order than was done initially.

This only matters in the Arduino IDE on the Rpi because if you have more than one of the same type there is no way to tell them apart other than knowing the order which you used to plug them in.

If you forget, then close the IDE, unplug them, then use

ls /dev/tty*

repeatedly to watch what changes as you plug them back in.

Then you can restart the IDE and they'll show up as available ports.