[TUHS] Shell control through external commands

Ronald Natalie ron at ronnatalie.com
Sun Sep 11 12:41:52 AEST 2016


> On Sep 10, 2016, at 10:39 PM, arnold at skeeve.com wrote:
> 
> "Ron Natalie" <ron at ronnatalie.com> wrote:
> 
>> Traditionally, the shell recognized shell scripts and ran them in a new
>> instance of the shell rather than calling exec on them.
> 
> I think that the way the shell "recognized" scripts was by having
> exec fail, otherwise how would it know?  I think we'll have to go
> grubbing in the source archives to be sure.
You are correct.

> 
>> It was a Berkeley hack to add a new exec magic number that happened to
>> correspond to the characters #!.
> 
> ISTR reading on this list that #! was a post-V7 Bell Labs invention
> that the BSD guys went and implemented themselves...

That’s possible.   We jumped from V7 to the BSD distributions because about the same time we were going from PDP-11’s to VAXen of various flavors
(actually our first VAX was a copy of one of the George Gobel dual processor 780’s).



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