Take the 2-minute tour ×
Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

I'm using Linux with a 3.9 kernel (BohdiLinux, but I'm looking for a distro (or at least desktop environment) agnostic answer).

Something is periodically (or on some event, perhaps) reseting the backlight level of my screen laptop, and I would like to know what process it is.

I naivly try to watch acess on /sys/class/backlight with inotifywatch[1], but events on /sys does not seems to be recorded.

I also try to see if there was some acpi events, but nothing was recorded by acpi_listen when the reset occures.

I have no idea of the process doing the reset, or even if it is always started or started on demand by another one, so I don't see how I could use lsof.

How could I progress from here ? Thanks for any advice !

[edit] :

[1] actual command: sudo inotifywatch -r -v /sys/class/backlight/

[2] actual command: sudo acpi_listen

[3] output

% sudo udevadm monitor --udev --property
monitor will print the received events for:
UDEV - the event which udev sends out after rule processing

UDEV  [27661.753446] change   /devices/pci0000:00/0000:00:02.0/backlight/acpi_video1 (backlight)
ACTION=change
DEVPATH=/devices/pci0000:00/0000:00:02.0/backlight/acpi_video1
SEQNUM=6027
SOURCE=sysfs
SUBSYSTEM=backlight
UDEV_LOG=7
USEC_INITIALIZED=27661753199
share|improve this question

2 Answers 2

Mount tmpfs at /sys/class/backlight/ and inotifywatch it. You may add some symlinks there as well.

share|improve this answer
    
I don't succeed in making it works, could you please give some more explanation about how it should work ? –  fanf42 May 5 '13 at 9:35

Have you tried top to see all running processes?

Also you can run ps -aux to get a snapshot of all running processes.

share|improve this answer
    
Yes, but both don't really fit for the task, as I don't know if it is a long running process or an ad hoc one, nor how it changes the backlight level. –  fanf42 May 5 '13 at 6:41

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.