blkid -o value

[Michael Conrad <mconrad@intellitree.com>]

Hi, I've just had a semi-serious problem related to blkid's "-o value" 
format.

When I first discovered that output format, I assumed that it would be a 
stable script-friendly output format intended for people who don't want 
to parse the name/value pairs.  The fields appeared to be
   LABEL
   UUID
   TYPE
and I wrote a script assuming the third one was TYPE.

However, suddenly the output has changed to be
   LABEL
   UUID
   SEC_TYPE <-- "ext2"
   TYPE <-- "ext3"

which caused my script to mount a ext3 partition as ext2, killing the 
journal.

Looking at the code, it appears that it iterates over some list coming 
from libblkid and prints a line with the value only if the value 
exists.  So it appears that there was never any intention of it being a 
stable output.

I would request that either the order of fields become stable by 
printing empty lines for missing fields (and documented), or the "-o 
value" be done away with, since I can't see any reason anyone would want 
random output in a script-friendly format, and the fact that it exists 
is likely to lead people astray.

Thoughts?  Comments?

-Mike Conrad