I read from a book says: "if the SETUID bit of a file is set, it runs as the owner of the file when ever executed by any user." So I login as root user and create a script named io_scan.sh, I have change the SETUID like this: chmod 4555 io_scan.sh but I still cannot run this script using other user except root. Can any one tell me what mistake I have made?

The contain of the io_scan.sh:
date >> /tmp/io_scan.txt
ioscan -fnC disk >> /tmp/io_scan.txt

When I do a long list of the two files:
ll /bin/io_scan.sh
-r-sr-xr-x 1 root bin 10 Jul 16 10:40 /bin/io_scan.sh

ll /tmp/io_scan.txt
-rw-r--r-- 1 root root 12 Jul 16 10:55 /tmp/io_scan.txt

Thanks for any help.

I guess the mistake that you have made is you have set the permission using root. So, now root becomes the owner of the file and any file on which root is the owner should not be executed by any other.

I tried it with other user and it worked.
It executed the process as the owner of the file and not the logged in user.

Hi Rajesh,

Thanks for the reply.

I have tried set the script with other user, inside the script there is a while loop and only one command whoami, I login with other user and run that script, the whoami return the logged in user, not the owner of the script, I grep the process and is run by the logged in user too. Can you tell me what you have tried? Please...