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Date: Mon, 21 Oct 2019 12:37:20 +1000
From: Warren Toomey <wkt@tuhs.org>
To: Ken Thompson via TUHS <tuhs@minnie.tuhs.org>
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Subject: Re: [TUHS] What was your "Aha, Unix!" moment?
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On Sun, Oct 20, 2019 at 07:31:55PM -0700, Ken Thompson via TUHS wrote:
> i was writing the small utilities for the first
> pdp-11 unix. (rm ls date ....)
> 
> so, cd was next.
> 
> % pwd
> /usr/ken
> % cd /tmp
> % pwd
> /usr/ken
> 
> Aha!

As in, 'cd' has to be built into the shell. If it's external, the forked
child gets to change directory and the parent shell doesn't. I'm just
putting this in for those who didn't spot the nuance immediately -- took
me a few tens of seconds.

But wasn't "chdir" built into the PDP-7 Unix shell?

Thanks, Warren