Permissions 101

[Bob Bernstein <poobah@ruptured-duck.com>]

I'm trying to understand the suid bit. So I created a little script to list
a file that I don't as a normal user have permission to read, namely
/var/log/user.log. Here's the data, starting with the permissions on
user.log:

$ ls -l /var/log/user.log
-rw-r-----    1 root     adm          2838 Jan 15 13:39 /var/log/user.log

Here's my little script "sutest", and its permissions, followed by the
results of executing it:

$ less sutest
#! /bin/bash
echo "does this work?"
less /var/log/user.log

$ ls -l sutest
-rwsr-xr-x    1 root     root          59 Jan 15 13:28 sutest

$ ./sutest
does this work?
/var/log/user.log: Permission denied

Can someone explain what's going on here? Is starting a shell the problem?

-- 
Bob Bernstein            "Sufficiently advanced file sharing systems 
at                        should be indistinguishable from corporate 
Esmond, R.I., USA         VPNs. Bless VPNs for creating all that 
                          suspicious-looking encrypted traffic." D.Marti