Hi there,
I have a question relating to SUID special permission.
I wanted to test its functionality and something doesn't work.

without SUID: script runs with the permissions of the user which starts the script
with SUID: the script runs with the permissions of the owner


I did the following test:

1. I have a directory named test (owned by root - 775 permissions) that contains 2 files: bar and foo.
2. bar is an executable file with only one command: rm foo
3. bar is owned by root (permission 4755) - SUID is set
4. foo is owned by root (permission 0400)
5. when a normal user runs bar, it should delete foo because it (bar) runs with the permissions of root (not the normal user which runs it). This happens only if the test directory has the appropiate rights for the normal user. Also if I add "chown user.user ." in doesn't work .
Under this conditions it seems that SUID doesn't work.

Please could any one clarify what I do wrong?
System in FC4.

Thanks

Afaik suid for shell scripts is disabled in most of linux distributions for security reasons.
Some workarounds are writing a short C wrapper or using sudo (recommended).

So I understand that SUID has no effect on shell scripts only on C programs (or related). Right?

That's right.
I believe (didn't try myself though, just read about it) you can also use suid with a perl script for example.