Re: [gentoo-user] How to set udev rule?

[Dirk Heinrichs <dirk.heinrichs@online.de>]

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Am Sonntag 30 August 2009 23:26:52 schrieb Alex Schuster:
> Jesús Guerrero writes:
> > On Sun, August 30, 2009 21:38, Dirk Heinrichs wrote:
> > > Am Sonntag 30 August 2009 19:29:39 schrieb Alex Schuster:
> > >> I have to change the bus from usb to scsi, then it works. But what
> > >> about unmounting? Is is possible to have it unmounted after I pull the
> > >> memory stick?
> > >
> > > How do want to umount something that's not there anymore? You have to
> > > umount _before_ you pull it.
> >
> > You can force the umount using -l (no, it's not documented in the man
> > page). You can use this to umount a volume *after* it has been physically
> > removed.
>
> The -l is not necessary here, a simple umount is enough.
>
> > And some people use this crap on udev rules to remove the
> > volume when they unplug the pendrive.
>
> Yes, this very rule would be nice to have :)

No, it would not. It can (and most likely will) lead to data loss.

> I do so, it makes me feel better, but I wonder whether it is _really_
> necessary.

Yes, it is. You never know when your data is written to physical storage 
unless you explicitely synced or umounted it while the device was still 
connected.

> I see Windows users do this all the time, without any problem
> yet. Of course, the wait a little after writing to it, but a few seconds
> after the blinking stops seem to be enough.

Usually it is, but you never know. Windows users don't have that broad choice 
of filesystems. They have NTFS and that's it, so they may know they're save. 
Linux filesystems may handle this differently, depending on which one you've 
chosen.

> And people are lazy, I know my
> Linux users _will_ just plug the stick. Using the KDE4 automounter, the
> device will be unmounted automatically in this case,

You mount filesystems, not devices. If you plug the device which holds the 
filesystem you've mounted, the fs can't be umounted anymore. There's nothing 
KDE automounter (aka HAL/DBUS) can do about it.

> but I am looking for a
> solution without KDE4, and as few user interaction as possible. The udev
> mouting rule is nice, but it leaves a lot of mounts when plugging in and
> out repeatedly.

Use the kernel automounter (autofs). It also umounts automatically (after a 
configurable time).

Bye...

	Dirk

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