Quite true. Thanks to both of you.

You need more trickery to achieve the other semantics. Probably not very portable and means there should be a special flag for "don't overwrite" mode.

 

% steph@ape2 (/home/stephan) %
% ll $0
lrwxrwxrwx 1 steph Ninguno 47 Mar  5 15:07 /bin/ksh93 -> /usr/ast-ksh9
+3s/arch/cygwin.i386/bin/ksh93s.exe

% steph@ape2 (/home/stephan) %
% echo foo > foo; echo bar > bar; /bin/ls -l foo bar; /bin/mv 0<&- 2>&
+- -i foo bar; cat -evnt bar
-rw-r--r-- 1 steph Ninguno 4 Jul 17 11:36 bar
-rw-r--r-- 1 steph Ninguno 4 Jul 17 11:36 foo
     1  bar$
[download]

Looking at version 3 of the single Unix Specification mv seems to indicate the above trick is ok from a standard perspective.

cheers --stephan