I hate to bitch but bitch I must

michael michael.copeland at gmail.com
Sat Oct 17 05:55:18 UTC 2009

PJ wrote:
> Why is it that the manual pages, as thorough as they may be, are very,
> very confusing.
> Perhaps I am being too wary, but I find that too many 
> instructions/examples are stumbling blocks to appreciation of the whole
> system:
> for instance, let's look at the instructions for changing disk labels
> with glabel or is it tunefs ?
> man glabel(8):
> for UFS the file system label is set with
> tunefs(8)
> <http://www.freebsd.org/cgi/man.cgi?query=tunefs&sektion=8&apropos=0&manpath=FreeBSD+7.2-RELEASE>.
> what happened to glabel?
> man tunefs(8)
> The *tunefs* utility cannot be
> run on an active file system. To change an active file system, it must
> be downgraded to read-only or unmounted.
> So, you have to run tunefs from an active file system to modify another
> disk?
> but from man tunefs:
> This utility should work on active file systems.
> What in hades does this mean--just above it says cannot be run on active
> file systems. ???
>  To change the root file
> system, the system must be rebooted after the file system is tuned.
> You can tune a file system, but you cannot tune a fish.
> How cute... And fish eat bugs.
> Seriously, now to the manual:
> To create a permanent label for a UFS2 file system without destroying
> any data, issue the following command:
> # tunefs -L /home/ /dev/da3
> Oh? home is what? What does this have to do with the partitions?
> Here's from man glabel(8):
> The following example shows how to set up a label for disk ``da2'', cre-
> ate a file system on it, and mount it:
> glabel label -v usr /dev/da2
> newfs /dev/label/usr
> mount /dev/label/usr /usr
> [...]
> umount /usr
> glabel stop usr
> glabel unload
> The next example shows how to set up a label for a UFS file system:
> tunefs -L data /dev/da4s1a
> mount /dev/ufs/data /mnt/data
> Am I to understand that glabel is only for a new system? What's with the
> newfs... I'm trying to set labels on an system that is already set up.
> And, the glabel examle above is not for UFS file systems? Oh, that's for
> tunefs?
> So why are we even dealing with this glabel?
> from manual:
> # tunefs -L /home/ //dev/da3/
> A label should now exist in /dev/ufs which may be added to /etc/fstab:
> /dev/ufs/home /home ufs rw 2 2
> Why? Is this necessary? and somewhere I saw "tunefs -L volume
> /dev/da0s1a" or something like that. Does that mean that each partition
> should be tunefsd? Maybe the guys who programmed this stuff understand;
> I sure don't. I just want to be able to set the labels according to what
> they say can be done... so shy not have a clear and concise explanation?
> Do people who write this stuff ever read it? Tell me that its clear and
> simple and to the point... so far, I have been running back and forth
> between half a dozen web pages trying to understand what is going on... 
> and doing things through a dense fog does not produce creative results!
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ok, in short since i didn't see anyone answer this directly, your 
question of tunefs vs glabel:

tunefs is for UFS: it labels a UFS filesystem, no matter the device, ie: 
ad or da. tunefs is part of the filesystem utilities for UFS.
good example, can't tunefs -L SWAP /dev/ad0s1b if it is a swap. you can 
glabel it.

glabel is for labeling a device itself. you can glabel an ntfs 
filesystem or ext2, whatever.

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