For example, in ZFS under FreeBSD and ZoL, there is a magic
.zfs dir inside of each zpool mountpoint and you can use
zfs set snapdir=visible to make that
.zfs dir visible.
What makes me curious is: if that setting is set to "hidden", how is the
.zfs dir actually hidden from the output of an
ls -a or shell path-auto-completion, while still being accessible otherwise (you can still
cd to it or call
stat on it)?
I can't really wrap my mind around this fact, because I somehow think if something is there and accessible it's supposed to be listed in
ls -a -- even if it's just magic/virtual in nature.
Can anybody explain how this works? Is there a POSIX conforming way to have a directory that is hidden from
ls -a while still being accessible? How do you do it?