Eu usaria df
para isso.
$ cd /usr
$ ls
X11R6 include libexec mdec sbin xobj
bin lib local obj share xsrc
games libdata lost+found ports src
$ for d in *; do test -d "$d" && df -P "$d" | awk -v d="$d" 'FNR>1{print d,$NF}'; done
X11R6 /usr
bin /usr
games /usr
include /usr
lib /usr
libdata /usr
libexec /usr
local /usr/local
lost+found /usr
mdec /usr
obj /usr
ports /usr/ports
sbin /usr
share /usr
src /usr
xobj /usr
xsrc /usr