On Thu, May 21, 2015 at 04:24:38PM +0800, Paul Wise wrote:
> In https://bugs.debian.org/784709 Jérôme Kieffer wrote:
>
> > Here is the answer for the 3.16 kernel:
> >
> > jerome@patagonia:~$ sudo blkid -o value -s TYPE /dev/sdb4
> > jerome@patagonia:~$ echo $?
> > 0
> ...
> >
> > The output is the same on 3.2, as you can see on attached images.
>
> Anyone know when blkid would return success but not the filesystem type?
The option '-s' does not affect return code, this option controls
output filter only. I have improved the description in the man page
to make it more obvious.
blkid returns success always when it's possible to gather any
information about the device. The important detail is that the recent
versions provide also PARTUUID=, so we have information about all
(including empty) partitions!
For example (very very old version from e2fsprogs):
# blkid /dev/sdc1; echo $?
2
but the current util-linux upstream:
#blkid /dev/sdc1; echo $?
/dev/sdc1: PARTUUID="4b6f59ea-01"
0
And yes, we have PARTUUID also for MBR partitions, the method used to
generate the UUID is the same like kernel uses for root= command
line option.
Note that my recommendation is to use lsblk, for example:
# lsblk --noheading --output FSTYPE /dev/sda1
vfat
it reads info from udev db (libblkid is only fallback here), and it
provides better way how to control output.
Karel
--
Karel Zak <k...@redhat.com>
http://karelzak.blogspot.com
--
To UNSUBSCRIBE, email to debian-boot-requ...@lists.debian.org
with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
Archive: https://lists.debian.org/20150521110735.ga4...@ws.net.home
