There are usually so many special cases to be dealt with when dealing with filesystems, that it doesn't make sense to try and use the same code on Win32 and *nix-like systems. So don't try:

if( $^O eq 'mswin32' ) {
     ## use xcopy
}
elsif( $^O =~ m[(linux|unix|whatever)] ) {
     ## use something else
}
else {
    ## use another something else
    ## or throw up your hands in disgust.
}
[download]

What do I mean by special cases?

1. *nix filesystems have:
   • a unified filespace;
   • soft & hard links;
   • chmod, chown, chgrp;
   • case-sensitivity;
   • Unicode filenames?;
   • other;
2. Win32 filesystems have:
   • drives;
   • UNCs;
   • shares;
   • substs;
   • junctions;
   • streams;
   • attributes;
   • ACLs;
   • case-transparency;
   • long & short filenames;
   • Wide-character filenames;
   • other;
3. Other non-disish/non-*nixish filesystems?

   ...

Mixing all the special cases together and trying to deal with them in-line, is an exercise in frustration & complexity and is doomed to years of bugs and failures.

Make a high-level, up-front decision as to which system you are on and then load a different module or use a different subroutine and keep the logic simple(r).