Writing to a “application/octet-stream” file on linux

问题

I am working on application which should block some USB devices.

I have found a way how could be blocking done. Problem is, as it's written here, that I need to write some string into /sys/bus/usb/drivers_probe file. Mentioned file is application/octet-stream and I can't find a way how to read or write to this file.

I have tried vim, echo, hexdump with sudo or as root, but every time I get "Permission denied" or "No such device" message. I did not tried it in C/C++, which is my app using, but I guess it would bring same result.

Can anyone help me understand how kernel developers meant writing to that file?

回答1:

If you get "Permission denied", it means you are not opening the file with root privileges:

$ sudo echo 4-1 > /sys/bus/usb/drivers_probe
bash: /sys/bus/usb/drivers_probe: Permission denied

$ echo 4-1 | sudo tee /sys/bus/usb/drivers_probe > /dev/null
(no error)

If you get "No such device", it means you are writing the wrong string:

$ echo 'foobar' | sudo tee /sys/bus/usb/drivers_probe > /dev/null
tee: /sys/bus/usb/drivers_probe: No such device

$ echo '3-1.3.1:1.3' | sudo tee /sys/bus/usb/drivers_probe > /dev/null
(no error)

来源：https://stackoverflow.com/questions/60725279/writing-to-a-application-octet-stream-file-on-linux