[TUHS] Shell control through external commands

Joerg Schilling schily at schily.net
Tue Sep 13 19:20:28 AEST 2016


Sven Mascheck <mascheck at in-ulm.de> wrote:

> On Mon, Sep 12, 2016 at 02:50:10PM +0200, Joerg Schilling wrote:
> > > > The colon was introduced by AT&T around 1983.
> > > 
> > > It's a builtin in the v7 Bourne shell - see SYSNULL in msg.c (which
> > > has the command name table) and in xec.c (which has the implementation)
> > 
> > You are missinterpeting things.
> > 
> > The colon in line one as a hint to a modified csh to call the Bourne Shell  
> > first appeared around 1983.
>
> I'm still confused (you're short with context): what does "introduced by AT&T" mean?
>
> I only know the #-hacked csh from 2BSD+ ('79), and the #-hacked sh from 3BSD+ ('80).
> How would ":" as a hint in this respect show up on other systems?

This is long ago, so my memory is not good anymore.

Aprox. 30 years ago, I ported my shell to a svr3 system and discovered problems.
AFAIR, this system had special treatment for scripts starting with ":".

Jörg

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