csh scripts on sys V question

[Griff Smith]

> In article <787 at chinet.UUCP> megabyte at chinet.UUCP (Dr. Megabyte) writes:
> >_IF_ I type "csh script".  Now, is there anyway for me to set up my 3b2 so that
> >I can just type "script" and have the proper shell chosen, either Bourne or
> >'C'? 
> 
> As I understand it the sh is started up to handle shell scripts, right?
> In Bezerkeley Unix I think the kernel figures out what program to exec.
> I don't see why the sh couldn't do this.  For instance, change the sh to
> look at the first line and exec it if the line is of the form
> 
> '#' '!' <program name>
> 
> and program name != '/bin/sh' or 'sh'
> 
> Anybody have any problems with this?
> -- 
> Larry McVoy 	        mcvoy at rsch.wisc.edu, 

It could, but the shell isn't the only path for program execution.  The
scheme in BSD (and V8, I think, (unless they took that one out too))
allows one to exec a shell script from within an arbitrary process.

There is also a bit of a problem with assuming that the shell's name is
/bin/sh.  We use two names: /bin/sh and /bin/ksh.  /bin/sh is the
blessed version of the Korn shell, /bin/ksh is the latest version from
Dave Korn.  Sometimes the two are linked, sometimes they're not.  The
shell may not know its name; the safest assumption is for it to use a
forked copy of itself only when there is no name on the initial comment
line.
-- 

Griff Smith	AT&T (Bell Laboratories), Murray Hill
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