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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?

0x2b3bfa0
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vinayawsm
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2 Answers2

7

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:

user.dz
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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.

Frantique
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  • I don't agree. The C++ program is a "command" after all. The user is asking for a solution to trigger that command. (He said: " But I wanted the program to run automatically whenever a flash drive is inserted. How could I do that?") – Frantique May 18 '15 at 13:51
  • For this[ http://ideone.com/uOReNj ] output of lsusb, what will be the values of XXXX and YYYY? – vinayawsm May 18 '15 at 13:59
  • If your pendrive is the Kingston than: XXXX= 0951, and YYYY =162f. – Frantique May 18 '15 at 14:18
  • For letting my code trigger for every different pen drive, should I always update the "my-usb-device.rules" file? – vinayawsm May 18 '15 at 14:38
  • YOu have to create rule for every device. Or better refactor your C++ code to run as daemon and observe the udev triggers. – Frantique May 18 '15 at 14:39