How to execute C++ program whenever a USB flash drive is inserted

Question

I have a C++ program that accesses USB pen drives/flash drives. It works for currently inserted flash drive. A normal C++ program doesn't execute until we run it. But I wanted the program to run automatically whenever a flash drive is inserted. How can I do that?

Answer 1

For general use, If you would like to run your program for any USB storage. Use the driver for the rule match.

1. Add a udev rules file

   sudo nano /etc/udev/rules.d/90-detect-storage.rules
   

2. Add this rule

   ACTION=="add", DRIVERS=="usb-storage", DRIVER=="sd", RUN+="/pathto/yourprogram"
   

   If you want your program to distinguish the disks, so it runs different operations, use (you can pass its serial number or any attribute you like):

   ACTION=="add", DRIVERS=="usb-storage", DRIVER=="sd", RUN+="/pathto/yourprogram $env{ID_VENDOR_ID} $env{ID_MODEL_ID}"
   

3. Reload all rules

   sudo udevadm control --reload-rules
   

4. Unplug and replug the flash drive

Notes:

• I used this rule just to test which create a log when the rule is triggered:

  ACTION=="add", DRIVERS=="usb-storage", DRIVER=="sd", RUN+="/bin/sh -c 'echo $env{ID_VENDOR_ID} $env{ID_MODEL_ID} >> /home/username/Desktop/usb-storage.log'"
  

• You can comment the rules you don't want by adding # to the beginning of the line. Rules file can contain multiple rules.

• To check all the available env variables, use:

  ACTION=="add", DRIVERS=="usb-storage", RUN+="/bin/sh -c 'echo == >> /home/username/Desktop/usb-storage-env.log; env >> /home/username/Desktop/usb-storage-env.log'"
  

• To check for parameters to use for rule match, run:

  sudo udevadm info --name=/dev/sdb1 --attribute-walk
  

References:

• Pass ATTR{idVendor} as argument in udev script
• Writing udev rules by Daniel Drake

Answer 2

You can use udev to run an albitrary command. To make it work, create a rule in /etc/udev/rules.d/:

sudo nano /etc/udev/rules.d/my-usb-device.rules

And enter:

ACTION=="add", ATTRS{idProduct}=="XXXX", ATTRS{idVendor}=="YYYY", RUN+="/location/of/my/command"

NOTE: The XXXX and YYYY values will be taken from lsusb output.