Before File::Spec, this is what I used. It still works today and it worked on very old perls on every Unix-like and Windows platforms that I've ever encountered.

Basically, the idea is to ask perl what it uses as directory separator char.

Sample use ($dirSep gets either back or forward slash character):

$dirSep = ( $ENV{"PATH"} =~ m/;[a-z]:\\/i ) ? '\\' : '/' ; 
print $dirSep;
[download]