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Description of problem:
blkid writes to default cache file, even when directed to write elsewhere

Version-Release number of selected component (if applicable):
2.17.2-12.9.el6_4.3

How reproducible:
every time

Steps to Reproduce:
$ sudo rm /etc/blkid/blkid.tab*
$ sudo blkid /dev/sda1 -w /dev/null -o value -s UUID
<UUID> is printed
$ cat /etc/blkid/blkid.tab 
<device DEVNO="0x0801" TIME="1378230067.254175" UUID="<UUID>" TYPE="ext4">/dev/sda1</device>

Actual results:
/etc/blkid/blkid.tab is created with a row for device requested

Expected results:
because -w /dev/null was specified, no cache should have been written

Additional info:
as a workaround, specifying -c /dev/null to not read the cache at all will prevent writing

This feature has never been implemented and the latest blkid versions (rhel7 and fedora) do not support -w at all.

Maybe we can update RHEL6 blkid.8 man page to document this behaviour. I don't think it make sense to do anything else. Sorry.

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

http://rhn.redhat.com/errata/RHBA-2014-1545.html