[LBo] 4.1.6 SUID

[Dave Lerner]

I did a simple test to see if the SUID flag would work.

I created a script /tmp/x with owner root, group root, permissions 755
and then turned on the SUID flag with the command "chmod u+s /tmp/x":

# ls -lF x
-rwsr-xr-x 1 root root 48 2006-11-18 17:45 x*

The contents of /tmp/x are:

#!/bin/sh
touch /tmp/z
echo ${UID}
echo ${EUID}

If I run the script from my normal non-root user, the output is:

$ ./x
1000
1000

And the file /tmp/z is created with my normal user as the owner, not root.

Why isn't the UID output as 0 (root's UID), and why isn't the file
/tmp/z owned by root?