What do I miss with SUID ?

[j.daniel]

Hello forum,

I am writing a script that I want to run with root privileges (yes I know, it is dangerous etc. - still, I want to do that). Perfect use of the SUID file permission I thought!

There is only one tiny problem; I can't make it run with root privileges!

An illustrating example; I created the following tiny script called iAm:



#! /bin/bash
whoami
# END


...change permissions & run:



$ chmod +x iAm
$ ./iAm
daniel


Perfect. I am daniel. Now let's change owner and set the suid bit:



$ sudo chown root:root iAm
$ sudo chmod u+s iAm
$ ls -lh
total 16K
-rwsr-xr-x 1 root root 47 2012-04-02 16:10 iAm


The moment of truth is approaching and...



$ ./iAm
daniel


???

What is it that I miss with the SUID bit? Isn't this file supposed to run as 'root'? (btw: Ubuntu 10.10)

Cheers!
/ Daniel

[Bachstelze]

The setuid bit does not work with scripts for obvious security reasons.

[j.daniel]

Awh! That just plain sucks. So setting the SUID bit of commands like nmcli would somehow be safer?

Anyway: thank you Bachstelze!

Cheers
/ Daniel