On Thu 07 Mar 2019 at 13:49:42 (-0700), Cousin Stanley wrote:
> David Wright wrote:
>
> > I prefer to populate fstab with canonical information
> > that actually belongs to the filesystems that are to be mounted.
>
> I don't understand what you're saying here.
>
> Does a disk label not belong to a filesystem
> that is to be mounted ?
Yes. Using a concrete example from /etc/fstab, in:
LABEL=sand1g /media/camera1g vfat
rw,errors=remount-ro,utf8,tz=UTC,shortname=lower,user,noauto,fmask=137,dmask=027
the characters sand1g have been written in the partition on the
device, an SD card. (The fact that they're lowercase means that
it's unlikely I wrote that LABEL in DOS or Windows.) But were
I to have put in /etc/fstab:
/dev/disk/by-label/sand1g /media/camera1g vfat
rw,errors=remount-ro,utf8,tz=UTC,shortname=lower,user,noauto,fmask=137,dmask=027
I would not expect to find the characters /dev/disk/by-label/ anywhere
in the partition. That string belongs to the linux system, not to
the card. That's what I meant by "actually belongs to the filesystems".
> > A filesystem that has a label,
> > has that label regardless of any OS.
> >
> > It's real, defined in the filesystem's documentation.
> >
> > All that stuff in /dev/disk/ is just an ephemeral
> > bunch of convenient symbolic links, presumably conjured
> > up by udev or somesuch, if not the linux kernel
>
> But are they not accurate after boot
> for particular disks on a particular machine ?
I don't question its accuracy.
> > I'm not clear about which other sort of label
> > might be referenced by LABEL=
>
> I'm not either but if I use /dev/disk/by-label
> I think I know what sort that is .... :)
OK, I thought you had something in mind.
BTW, in looking at man mount (to remind myself of the -L option),
I noticed that it actually mentions this business:
"The recommended setup is to use tags (e.g. LABEL=label) rather
than /dev/disk/by-{label,uuid,partuuid,partlabel} udev symlinks in
the /etc/fstab file. Tags are more readable, robust and portable."
Cheers,
David.
