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Re: output from udevadm

On Sun, Jul 11, 2010 at 5:23 PM,  <peasthope@shaw.ca> wrote:
> The following short transcript is from adapting the udevadm
> invocation in http://wiki.debian.org/udev to investigate
> 1394 support in my Squeeze system.  Two questions.
> * What exactly is meant by "device specified by the devpath" in
>  the output?  According to the udevadm man page, devpath is
>  the value assigned to --path;  but that parameter is not present
>  in the command below.  No devpath is specified.
> * What exactly is '/class/ieee1394_protocol/raw1394'?
>  /class is not a directory in the filesystem and /dev/raw1394
>  is the only 1394 device I've found.
> ======= transcript=======
> joule:/dev# udevadm info --name=/dev/raw1394 --attribute-walk
> Udevinfo starts with the device specified by the devpath and then
> walks up the chain of parent devices. It prints for every device
> found, all possible attributes in the udev rules key format.
> A rule to match, can be composed by the attributes of the device
> and the attributes from one single parent device.
>  looking at device '/class/ieee1394_protocol/raw1394':
>    KERNEL=="raw1394"
>    SUBSYSTEM=="ieee1394_protocol"
>    DRIVER==""
> joule:/dev# ls /class
> ls: cannot access /class: No such file or directory
> joule:/dev#

>From a filesystem perspective, there is an assumed /sys "in front of" /class/...

devpath is the /class/... equivalent of /dev/...

You can get it with
udevadm info --query=path --name=/dev/...

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