Preventing udev from creating device entries under /dev

alienDog · 05-21-2010, 06:08 PM

Hi,

I need to prevent udev from creating the /dev/v4l/by-path/* and /dev/v4l/by-id/* files upon connecting my webcam. The problem is that Kopete doesn't want to display the video if these files are present. It works fine if I remove them, but I'd rather not have them created in the first place, since they seem to be completely useless anyway.

Matir · 05-21-2010, 08:36 PM

Override the rules for your device in /etc/udev/rules.d. There are options to end processing that should prevent the symlinks from being created.

catkin · 05-21-2010, 11:16 PM

Quote:

Originally Posted by Matir

Override the rules for your device in /etc/udev/rules.d. There are options to end processing that should prevent the symlinks from being created.

The current effective rule(s) may be in /lib/udev/rules.d

alienDog · 05-22-2010, 07:05 AM

The correct place is /lib/udev/rules.d, like catkin suggested (is this distribution dependent?). Removing 60-presistent-v4l.rules file from that directory prevents the /dev/v4l files from being created and the webcam works like charm.

Thank you guys

catkin · 05-22-2010, 08:37 AM

Quote:

Originally Posted by alienDog

The correct place is /lib/udev/rules.d, like catkin suggested (is this distribution dependent?).

Glad you found a solution

According to the udev man page "The udev rules are read from the files located in the default rules directory /lib/udev/rules.d/, the custom rules directory /etc/udev/rules.d/ and the temporary rules directory /dev/.udev/rules.d/. All rule files are sorted and processed in lexical order, regardless in which of these directories they live". So both locations are correct and neither takes precedence.

It may be that the /lib/udev/rules.d/ is the preferred location for rules created during installation and upgrade while /etc/udev/rules.d/ is the preferred location for local customisation. This theory is based on most of the files in the lib directory on Slackware 13.0 starting with the comment "# do not edit this file, it will be overwritten on update".