[TUHS] v7 source code for sh

Sven Mascheck mascheck at in-ulm.de
Sun Feb 20 09:11:59 AEST 2022

On 19.02.2022 23:39, John Cowan wrote:
> On Sat, Feb 19, 2022 at 1:45 PM Rob Pike <robpike at gmail.com> wrote:
>     I undid all the macros for the v8 shell, with Steve's blessing,
>     before doing the key work on that shell. But no one outside cared
>     about any of the research Unixes after v7,
> Lots of us would have loved to care about them and were sad that we 
> couldn't until they were open sourced much later.

8th ed sh (about '84) brought quite a few changes and fixes. Just naming 
a few:
- environment variable HISTORY, pointing to a writable file, providing a 
history mechanism by means of "=(1)"
- type is replaced by whatis, which produces output that can be 
re-evaluated by the shell
- functions can be exported, in the same ways like variables

keyword history: I always imagined that the Bourne shell would have been 
in much wider use even nowadays, if only it had provided line editing 
and a history at some point. Why not? Even Kenneth Almquist released his 
SVR4-like reimplementation intentionally without history. All that might 
have been implemented more elegant directly in the terminal I/O instead 
of in every program? (that is, not in a MS-DOS-like way, where every 
program even needs its own pager).

I still wonder if it would be possible to properly provide line editing 
and history in the terminal I/O in general.

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