Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!cs.utexas.edu!uunet!auspex!guy
From: guy@auspex.auspex.com (Guy Harris)
Newsgroups: comp.unix.shell
Subject: Re: how to setuid for shell scripts on ultrix?
Message-ID: <4635@auspex.auspex.com>
Date: 2 Dec 90 20:57:18 GMT
References: <1990Nov15.181448.23231@mdivax1.uucp> <4438@auspex.auspex.com> <144@raysnec.UUCP>
Organization: Auspex Systems, Santa Clara
Lines: 16

>	If that's the case, then why are they not supported by default on
>	non-BSD systems (like System III and V)?

BSD-style "#!" is not supported, *PERIOD*, in System III as it came from
AT&T, nor is it supported in any version of System V from AT&T prior to
System V Release 4. 

Therefore, set-UID shell scripts on those systems have to be supported
using some other mechanism, and AT&T doesn't supply any such mechanism
with any of those releases.

That's why they're not supported by default in those systems; it's
because they're not supported *at all* in those systems - you have to
add your own mechanism to support them.  *Some* vendors have added
BSD-style "#!" to them (AT&T being the vendor who did so in S5R4);
others haven't.