$ ### This is a current Debian testing from 2007-04-13 with kernel...
$ uname -a
Linux leksak 2.6.16-2-amd64-k8-smp #1 SMP Fri Aug 18 21:10:33 CEST 2006 x86_64 GNU/Linux
$ ### Some preparation:
$ whoami
sbeyer
$ cd /tmp
$ mkdir foo
$ chmod 0700 foo
$ cd foo
$ mkdir bar
$ chmod 0777 bar 
$ cd bar
$ mkdir dir
$ echo test > file
$ ls
dir  file
$ su
Password: 
# ### Now look at this:
# su -s /bin/sh nobody
$ ls
dir  file
$ pwd
/tmp/foo/bar
$ ls `pwd`
ls: /tmp/foo/bar/: Permission denied
$ cat file
test
$ cd dir
sh: cd: dir: Not a directory
$ cd ..
sh: cd: ..: Not a directory
$ cd /tmp/foo/
sh: cd: /tmp/foo/: Permission denied
$ cd /tmp/    
$ cat foo/bar/file
cat: foo/bar/file: Permission denied
$ exit
$ exit