% mkdir foo bar baz
% dd if=/dev/zero of=foo/test bs=1024 count=10000
10000+0 records in
10000+0 records out
10240000 bytes (10 MB) copied, 0.0176239 s, 581 MB/s
% (cd bar; ln -s ../foo/test)
% (cd baz; ln -s ../foo/test)
% du -hc bar baz
4.0K    bar
4.0K    baz
8.0K    total
% du -hc --dereference bar baz
9.8M    bar
4.0K    baz
9.8M    total