determining this UUID stuff

[Chris Tyler]

On Sun, 2009-04-26 at 05:52 -0700, Craig White wrote:
> On Sun, 2009-04-26 at 01:31 -0700, jdow wrote:
> 
> > $blkid /dev/sda1
> > /dev/sda1: LABEL="/boot-7" UUID="bfe129cd-8087-4c0b-aad1-08508b7adee2" 
> > SEC_TYPE="ext2" TYPE="ext3"
> > 
> > It works by partition not drive.
> ----
> I think it is more like, you won't see the results you expect if you
> supply /dev/sdX as the argument because /dev/sdX is a physical device
> and not a block device to Linux.

Physical drives are block devices too:

$ ls -l /dev/sda
brw-rw---- 1 root disk 8, 0 2009-04-25 18:06 /dev/sda

Note the 'b' at the start of the output line.

Filesystem or swap formatting *may* be applied at the drive level, but
is almost always applied at the partion level, so in the vast majority
of cases you will need to supply a partition ID to the blkid command
(ie., the argument to blkid needs to be the same argument that was
supplied to mkfs or mkswap -- drive if the drive was formatted,
partition if a partition was formatted, LV if an LV was formatted).

-Chris