How to restrict users so that they can only execute commands from /bin?

I was provided an assignment with several questions. One of the questions is: > How to restrict users can only execute the commands in the directory /bin? I tried to solve it by using the following commands, but they did not work.

-none
# useradd -s /bin/bash localuser
# usermod -s /bin/rbash localuser
# mkdir /home/localuser/programs

Here are the contents of /home/localuser/.bash_profile:

-bash
# .bash_profile  

# Get the aliases and functions  
if [ -f ~/.bashrc ]; then  
. ~/.bashrc  
fi  
# User specific environment and startup programs  
PATH=$HOME/programs  
export PATH

Then I tried:

-none
[localuser@example ~]$ ls  
-rbash: ls: command not found  
[localuser@example ~]$ less file1  
-rbash: less: command not found  
[localuser@example ~]$ clear  
-rbash: clear: command not found  
[localuser@example ~]$ date  
-rbash: date: command not found  
[localuser@example ~]$ ping redhat.com  
-rbash: ping: command not found
# ln -s /bin/date /home/localuser/programs/  
# ln -s /bin/ls /home/localuser/programs/  
# ll /home/localuser/programs/  
total 8  
lrwxrwxrwx 1 root root 9 Oct 17 15:53 date -> /bin/date  
lrwxrwxrwx 1 root root 7 Oct 17 15:43 ls -> /bin/ls
[localuser@example ~]$ date  
Mon Oct 17 15:55:45 IST 2011  
[localuser@example ~]$ ls  
file1 file10 file2 file3 file4 file5 file6 file7 file8 file9 programs  
[localuser@example ~]$ clear  
-rbash: clear: command not found
# chattr +i /home/localuser/.bash_profile

What would be your answer?