LinuxQuestions.org - A question on SUID (Set User ID)

Friends,

Suppose root user is setting a file script.sh with SUID permission and allowing others to have execute permissions as follows:

Code:

 #ls -l /script.sh

-rwsr--r-x root root ---- script.sh

And then he is writing a script as follows:

Code:

#vi /script.sh

        #!/bin/bash

        touch /root/newfile.txt

        :wq!

Now, a normal user is logging in and executes that file:

Code:

#su - normaluser

[normaluser@linux1~]$cd /

[normaluser@linux1~]$./script.sh

touch: cannot touch `/root/newfile.txt': Permission denied

Actually, after setting SUID to a script, and if a normaluser executes that file, he should be able to write a file inside /root directory, since the effective UID is that of root user's. why is it not happening in this case? Please help.