SUID permission on Bash script

[Giorgos Keramidas]

On Fri, 28 Aug 2009 09:24:35 +0100, Jeronimo Calvo <jeronimocalvop at googlemail.com> wrote:
> Hi folks!
>
> Im trying to set up a reaaallly basic scrip to allow one user to shutdown my
> machine without root permisions, seting up SUID as follows:
>
>
> -rwsrwxr-- 1 root wheel 38 Aug 27 23:12 apagar.sh
>
> $ ./apagar.sh
>
> Permission denied
>
>
> content of script:
>
>
> cat apagar.sh
>
> ]#!/usr/local/bin/bash
> shutdown -p now
>
> As far as i know, using SUID, script must runs with root
> permissions... so i shoudnt get "Permission denied", what im doing
> wrong??

No it must not.  There are security reasons why shell scripts are not
setuid-capable.  You can find some of them in the archives of the
mailing list, going back at least until 1997.

The good thing is that you don't need a shell script to do that.  You
can install `sudo' and give permission to the specific user to run:

    sudo shutdown -p now