Re: matching udev attribute keys

[Camaleón <noelamac@gmail.com>]

On Mon, 27 Dec 2010 13:20:37 -0500, Tom H wrote:

> On Mon, Dec 27, 2010 at 10:17 AM, Camaleón <noelamac@gmail.com> wrote:
>> On Sun, 26 Dec 2010 15:58:08 -0800, briand wrote:
>>
>>> how do I know that "SerialNumber" is a valid udev key other than the
>>> fact that it is listed in dmesg when the device is plugged in.
>>
>> For instance, my USB key has at least one "ATTRS{serial}" value:
>>
>> sm01@stt008:~$ udevinfo -a -p /sys/block/sdc | grep serial
>>    ATTRS{serial}=="0000:00:1a.7"
>>
>> But not my internal hard disks, neither from udevinfo:
>>
>> sm01@stt008:~$ udevinfo -a -p /sys/block/sda | grep serial
>> sm01@stt008:~$ udevinfo -a -p /sys/block/sdb | grep serial
>> sm01@stt008:~$
> 
> Question:
> 
> You use the equivalent of "udevadm info --attribute-walk
> --path=/sys/block/sda".
> 
> What if you use "udevadm info --query=property --path=/sys/block/sda"
> and it outputs an "ID_SERIAL"? Can it be used in a udev rule?

I'd say yes, provided it is an ENV (E) key and you write the propper rule:

http://www.reactivated.net/writing_udev_rules.html#env

Look:

stt008:~# udevadm info --query all --name=/dev/sdb
P: /block/sdb
N: sdb
S: block/8:16
S: disk/by-id/ata-ST3500320NS_xxxxxxxx
S: disk/by-id/scsi-SATA_ST3500320NS_xxxxxxxx
S: disk/by-path/pci-0000:00:1f.2-scsi-1:0:0:0
E: ID_VENDOR=ATA
E: ID_MODEL=ST3500320NS
E: ID_REVISION=SN06
E: ID_SERIAL=SATA_ST3500320NS_xxxxxxxx
E: ID_SERIAL_SHORT=xxxxxxxx
E: ID_TYPE=disk
E: ID_BUS=scsi
E: ID_ATA_COMPAT=ST3500320NS_xxxxxxx
E: ID_PATH=pci-0000:00:1f.2-scsi-1:0:0:0

"P" must be "path", "N" must be "name", "S" must be "symlink" and "E" has 
to be "environment".

Greetings,

-- 
Camaleón