how to know a usb device is plugged in/out
 

Hello,

My application needs to be notified when a usb device is plugged in/out. I know the file /proc/bus/usb/devices is changed whenever a usb device is plugged in/out. But how do I know the file is changed. May I use poll(() function to wait for the file changing? (I don't want to read the file every second to see the chaning.)

Thanks in advance.

not sure if you're going from a programming angle with the references to poll() there, but i'd suggest you look toward udev rules, assuming you're using udev of course. in a specific rule you can set a PROGRAM= variable to run a script on a device being connected. not sure about disconnection, as i've never done it, but i expect it's simple.

Your guess is correct. My question is about programming. My application needs to monitor usb devices plugged in/out. And I don't think I can use udev since my kernel is 2.4.28. Thanks anyway.