Linux can format an (external) disk as HFS+, e.g.:
apt-get install gparted hfsprogs, then
gparted /dev/sdd, rightclick on the partition to format, choose HFS+, click Apply, quit;
mount -t hfsplus /dev/sdd2 /mnt/foo.
But then you can't make both
/mnt/foo/XYZZY, because gparted used macOS's default option, case-insensitive. So copying files onto it from Linux causes all sorts of problems.
Can Linux format it as case sensitive?
Or must I plug the disk into a Mac to format it like that?