linux - SUID not working with shell script

Question

I have created a small shell script with the following content:

cat /usr/bin/checksuid.sh

!/bin/bash
echo "Hello" > /etc/myfile.cnf

ls -l /usr/bin/checksuid.sh
-rwsr-xr-x 1 root root 56 Sep  9 12:56 /usr/bin/checksuid.sh

I have also created a file /etc/myfile.cnf with root account and set permissions as below:

-rw-r--r-- 1 root root 6 Sep  9 12:26 /etc/myfile.cnf

When I execute /usr/bin/checksuid.sh from a non-root account, I get the following error:

/usr/bin/checksuid.sh: line 3: /etc/myfile.cnf: Permission denied

Can some one help you that why SUID is not working?

Answer 1

Shell scripts can't be SUID. See http://www.faqs.org/faqs/unix-faq/faq/part4/section-7.html