I had an assumption that perl could be portable across various OS - but apparently not that easily.

Right. Perl was written on Unix systems and tries really hard to provide that interface even on other systems. But Windows really sucks at being a Unix. ;-) Your best best may be one of the modules with Win32 in its name. To find the name of a files owner, you need to call a different function on Windows.

See also perlport and the links at the end of that document.

Alexander