$ mkdir foo foo/bar foo/baz foo/bat
$ cd foo
$ chmod 000 bar
$ ls -al
total 44
drwxr-xr-x 5 marco marco  4096 2012-08-18 22:07 .
drwxr-xr-x 4 marco marco 28672 2012-08-18 22:07 ..
d--------- 2 marco marco  4096 2012-08-18 22:07 bar
drwxr-xr-x 2 marco marco  4096 2012-08-18 22:07 bat
drwxr-xr-x 2 marco marco  4096 2012-08-18 22:07 baz

##</code><code>##

$ cd baz
$ ln -s ../bar bar
$ ln -s ../bat bat
$ ls -al
total 8
drwxr-xr-x 2 marco marco 4096 2012-08-18 22:08 .
drwxr-xr-x 5 marco marco 4096 2012-08-18 22:07 ..
lrwxrwxrwx 1 marco marco    6 2012-08-18 22:08 bar -> ../bar
lrwxrwxrwx 1 marco marco    6 2012-08-18 22:08 bat -> ../bat

##</code><code>##

$ touch t
$ cp t bat
$ cp t bar
cp: cannot stat `bar/t': Permission denied
$ ls bat
t
$ ls bar
ls: cannot open directory bar: Permission denied