Sv.2 suid bits

[Doug Gwyn <gwyn>]

> Suid bits don't work on shell scripts on Sys 3 or Sys 5, I suppose this is
> for security reasons.  As far as I know, they don't work on any AT&T UNIX.

Since the script is interpreted by the shell, and since the shell
does not run set-UID itself, of course you can't have set-UID
shell scripts.  For that to work, the kernel itself would have
to run the shell for you (as in 4.2BSD for #! magic numbers),
after establishing suitable privilege for it.

The shell was not designed with this usage in mind, so it has
numerous security loopholes.  Closing them all is a big task.