> Listen.  You're the one who is calling mv with invalid arguments in the
> first place, so don't get sarcastic when people don't want to modify it
> not to object...

Invalid arguments?

The last time I read the mv manual page, it was more than happy to accept,
as arguments, the name of an existing file and the name of an existing
directory, in that order.  For the case in question, it sure looks to me
like the arguments (a file, and a directory on another disk) are perfectly
*valid*.

READ THE MANUAL PAGE.  I *defy* you to justify ANY ERROR MESSAGE WHATSOEVER
simply because the file which is the source is not owned by the user running
"mv".

QUITE TO THE CONTRARY, I claim that the manual page states that absolutely
no message is permitted, because the mv(1) manual page explicitly defers to
the cp(1) manual page, which explicitly says that no message is displayed.

I repeat, I defy you to justify printing an error message based on the
documented behavior.  If you choose to claim that the documentation is wrong,
I then ask you to justify breaking shell scripts that have been around longer
than NetBSD has.