Re: [9fans] unix RC shell bug

[Byron Rakitzis <byron@rakitzis.com>]

>iirc $" was not implemented in the unix rc.
>
>back in '91 (when byron released it) $" did not exist.
>i'm not sure when it was added to the plan 9 rc.
>sometime after '93 i'd guess.

I came up with $^ in rc early on. I don't have any records to show when
this first appeared, but I found an old version of rc on funet.fi, rc-1.2,
which showed this feature in 1991. Given that the work on the shell
started in the fall of 1990 this was really very early on in its life.

With some modesty I suggest that maybe this was back-ported into plan 9
from my reimplementation with a new syntax. Or maybe they came up with
the idea independently. The need for it is fairly obvious.

I chose $^ by analogy with the ^ concatenation operator, and because it
leaves the " character still uninterpreted by rc.

In general there are some incompatabilities between my rc and plan9's,
in particular with regards to the "if not" syntax. This has caused
some friction over the years, but never enough in my opinion to warrant
changing the code I wrote.

Byron.