/lib/udev/rules.d/60-persistent-v4l.rules is in udev 175-0ubuntu9.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 | # do not edit this file, it will be overwritten on update
ACTION=="remove", GOTO="persistent_v4l_end"
SUBSYSTEM!="video4linux", GOTO="persistent_v4l_end"
ENV{MAJOR}=="", GOTO="persistent_v4l_end"
IMPORT{program}="v4l_id $tempnode"
SUBSYSTEMS=="usb", IMPORT{builtin}="usb_id"
KERNEL=="video*", ENV{ID_SERIAL}=="?*", SYMLINK+="v4l/by-id/$env{ID_BUS}-$env{ID_SERIAL}-video-index$attr{index}"
# check for valid "index" number
TEST!="index", GOTO="persistent_v4l_end"
ATTR{index}!="?*", GOTO="persistent_v4l_end"
IMPORT{builtin}="path_id"
ENV{ID_PATH}=="?*", KERNEL=="video*|vbi*", SYMLINK+="v4l/by-path/$env{ID_PATH}-video-index$attr{index}"
ENV{ID_PATH}=="?*", KERNEL=="audio*", SYMLINK+="v4l/by-path/$env{ID_PATH}-audio-index$attr{index}"
LABEL="persistent_v4l_end"
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