I ran your code (in Cygwin's shell), Fletch, thanks. My directories are absolute paths:

$ abs_path `perl -MConfig -le 'printf "%s %s", $Config{installprivlib}, $Config{installarchlib}'`
/usr/share/perl5/5.40
/usr/lib/perl5/5.40/x86_64-cygwin-threads

I tried an idea that occurred to me (and is indirectly suggested by Dave above). The 'nix command du:

 
$ du -sh `perl -MConfig -le 'printf "%s %s", $Config{installprivlib}, $Config{installarchlib}'`
27M     /usr/share/perl5/5.40
24M     /usr/lib/perl5/5.40/x86_64-cygwin-threads

I'd say that du is doing something different (and what I want) from what Filesys::DfPortable dfportable is doing. The above question from Dave is on target. The two dirs are on the same filesystem. I was naively believing that I'd get the sum of the usage of each directory tree, not of the entire filesystem containing the directory tree(s). A significant distinction, eh. Despite the use of the term Filesys. Ok, that warrants a duh.

    – Soren
Mar 10, 2026 at 16:21 UTC