derez peculiarity

[Bob Lantz]

Mark,

You (sysmark at physics.utoronto.ca) wrote:

>Why on earth can't I use derez if I'm not invoking it from a window on
>the console?

Derez is a Macintosh program, an MPW tool in fact.  In order to run it,
you need to be running the Macintosh environment.

>If I rlogin onto an A/UX system from my workstation, and
>try to run derez, I get the following error message:

>	Can't open user interface device
>	/dev/uinter0: Permission denied

I agree that this error message is somewhat unenlightening.  It
should be something like

"derez: Sorry, you may not start up a program in fred's Macintosh environment."

>First of all, what is /dev/uinter0?

/dev/uinter0 is the interface to the user interface "device" driver.

>  It's not documented in section 7 of
>the System Administrator's Reference manual.

It is documented, I believe, in the (famous) _A/UX Toolbox: Macintosh ROM 
Interface_ manual (see section C, Implementation Notes.)

>At the moment, it's owned
>by the person who is currently logged in on the console; protection mode
>is 0600.

Yes. The person who is currently logged in on the console "owns" the
Macintosh environment.   Users are not normally permitted to start
up programs in another user's Macintosh environment.

>Secondly, why does derez even care about /dev/uinter0?  Is there a good
>reason (and, if so, what?), or is it just a bug?
>Finally, what other A/UX commands have this (mis)feature?

See above.  The same applies to MacWrite, MacPaint, or any Macintosh
binary which you are running on A/UX.  A/UX allows you to start Macintosh
programs from the shell, but you must be running the Macintosh environment.

I hope this clears things up.

>Mark Bartelt                                                416/978-5619
>Canadian Institute for                             mark at cita.toronto.edu
>Theoretical Astrophysics                           mark at cita.utoronto.ca

Bob