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Re: Bug#104186: apt-cdrom: u/mount equivalents for the Hurd



On Fri, Jul 13, 2001 at 12:36:33AM +0200, Robert Bihlmeyer wrote:
> [CCing and R-T debian-hurd. Please direct followups there, as I
> think this issue has little to do with the bug at hand, and people
> there can probably answer your question much better, too.]
> 
> Adam Heath <adam@lapdoog.doogie.brainfood.com> writes:
> 
> > So why can't there be a  umount compatiblity shell script?

Please understand that we are trying to improve the quality of your
software.  Instead bending back- and forwards and trying to make the Hurd
look like any other Unix even where there is little sense to do so, we point
out where you make assumptions about the system which are not defined in any
standard whatsoever.[1]  We do this for your benefit also.

> > This changes how all unix admins expect unix to work.

For umount, this holds anyway, even if we would provide a wrapper.  A
wrapper would only be a very poor copy of the real thing on Unix.  For
example, it would only work with the path name, not with the device file.
In fact, the whole notion of mounting and unmounting devices with a certain
filesystem (implemented in the kernel) is not carrying over to the Hurd.

Not only would the hypothetical umount wrapper do a poor job for Unix
enthusiasts, it would also do a poor job for the Hurd, as there is no way it
could be as flexible as our current tools (settrans, fsysopts, showtrans)
already are.  People would rightly complain what a useless thing this umount is
on the Hurd, and probably miss out on the exciting flexibility of the real
thing.

I am sorry if this is not the answer you expected.  I invite you to become
more familiar with the Hurd translator concept
(http://www.gnu.org/software/hurd/whatis/translator.html) and with the Hurd
in general.  Hopefully you will then realize why the lack of umount is just
a logical conclusion from a deep and original design decision, which lies at
the heart of the Hurd system.

Thanks,
Marcus

[1] We claim that the Hurd is POSIX compliant.  I checked, and neither the
current draft 6 of POSIX as used by the Austin group, nor the current Single
Unix Specification defines umount or even mount.  For mount, we have a
wrapper because it was easy to do so.  It is merely an example for the more
generic settrans utility.

-- 
`Rhubarb is no Egyptian god.' Debian http://www.debian.org brinkmd@debian.org
Marcus Brinkmann              GNU    http://www.gnu.org    marcus@gnu.org
Marcus.Brinkmann@ruhr-uni-bochum.de
http://www.marcus-brinkmann.de



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