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I've got a few usb webcams, but unfortunately they have no serial numbers. So upon boot they tend to switch device file names.

Since they'll always be in the same usb port I want to create a rule based on that. But it's failing miserably.

Here's what I tried so far:

# /sys/bus/usb/devices/2-5.1:1.1/uevent
#SUBSYSTEM=="usb", SYSFS{idVendor}=="05e1", SYSFS{idProduct}=="0408", PLACE=="2-5.1", NAME="video98"
#SUBSYSTEM=="usb", PLACE=="2-5.1", NAME="video98"
#SUBSYSTEM=="usb", ATTR{busnum}="002", ATTR{devnum}="009", ATTR{idVendor}="05e1", NAME="video98"
SUBSYSTEM=="usb", ATTR{busnum}="002", ATTR{devpath}="/devices/pci0000:00/0000:00:1d.7/usb2/2-5/2-5.1", ATTR{idVendor}="05e1", NAME="video98"

# /sys/bus/usb/devices/2-5.3:1.1/uevent
#SUBSYSTEM=="usb", ATTR{busnum}="002", ATTR{devnum}="010", ATTR{idVendor}="05e1", NAME="video99"
SUBSYSTEM=="usb", ATTR{busnum}="002", ATTR{devpath}="/devices/pci0000:00/0000:00:1d.7/usb2/2-5/2-5.3", ATTR{idVendor}="05e1", NAME="video99"

So yeah, I've made a few attempts. I've seen that devnum also changes on boot, so I don't want to use that.

I actually just want to use the "2-5.3" and "2-5.1" thing. That's always the same. But how?

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1 Answer

up vote 0 down vote accepted

I've done almost exactly this before, weirdly enough. Mine were external hard drives, but it shouldn't be any different for USB cameras. I used the SCSI bus addresses for the ports, which worked well.

I got my info using lsscsi, which will print something like the following for a USB device:

[2:0:0:0] disk <descriptor> <dev name>

Then something similar the following rule should do what you want:

SUBSYSTEM=="usb", KERNEL=="sd*1", KERNELS=="2:0:0:0", SYMLINK+="<label_1>"

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