From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-0.5 required=5.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,PLING_QUERY, RCVD_IN_DNSWL_NONE autolearn=ham autolearn_force=no version=3.4.2 Received: from minnie.tuhs.org (minnie.tuhs.org [45.79.103.53]) by inbox.vuxu.org (OpenSMTPD) with ESMTP id 8e46158f for ; Tue, 22 Oct 2019 06:37:35 +0000 (UTC) Received: by minnie.tuhs.org (Postfix, from userid 112) id E97E99BA0B; Tue, 22 Oct 2019 16:37:33 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id 59C4493D91; Tue, 22 Oct 2019 16:37:08 +1000 (AEST) Authentication-Results: minnie.tuhs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=ewe2.ninja header.i=@ewe2.ninja header.b="sa9hxrw6"; dkim-atps=neutral Received: by minnie.tuhs.org (Postfix, from userid 112) id 0B85993D91; Tue, 22 Oct 2019 16:37:06 +1000 (AEST) X-Greylist: delayed 439 seconds by postgrey-1.36 at minnie.tuhs.org; Tue, 22 Oct 2019 16:37:05 AEST Received: from mail.ewe2.ninja (ewe2.ninja [38.240.3.172]) by minnie.tuhs.org (Postfix) with ESMTPS id 90BB993D8C for ; Tue, 22 Oct 2019 16:37:05 +1000 (AEST) Received: by mail.ewe2.ninja (Postfix, from userid 1001) id 4D56B411CF; Tue, 22 Oct 2019 02:29:44 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=ewe2.ninja; s=mail; t=1571725784; bh=b0ejdoDGfowuQ6A9i2FHgvJqinJy5YrryFiuuK4YpkA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=sa9hxrw6aWLEI61YHWfu0IAFhYPByZlB7slRiyubCL2RAjr92xPubsn8jMWBttZoX NbISmNHR/s11jfVJlhFnpXKHjYRIGg0YPxjlEpdva2Tu5PRO5gNaIToaOQfJ0s3iAX 8QQJnvUjsCGHMX8S84e5ODk7X14t2b6e7Bl7tDrstfXMhvdyPsbE/FAvRpagXYjS47 ryd4doNjyHVEHFAz9UJK9FVc0okQqTj86BBKG2hjSk8v/fnqAkpzOaH1rcWq7VVW+E rFkgSXaqrESG5dfARwZVVvWJCAhgqsUVBTvGj0DYT40Kaw68ur+09SzDHo81o/VI6F 3njC6wciJkiYQ== Date: Tue, 22 Oct 2019 02:29:44 -0400 From: Sean Dwyer To: Warren Toomey Message-ID: <20191022062944.GA26946@mail.ewe2.ninja> References: <1571599556.22415.for-standards-violators@oclsc.org> <20191020201219.GA5035@mail.ewe2.ninja> <20191021023720.GA12808@minnie.tuhs.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191021023720.GA12808@minnie.tuhs.org> X-Homepage: https://ewe2.ninja X-Operating-System: Linux, kernel 5.2.0-3-amd64 User-Agent: Mutt/1.10.1 (2018-07-13) Subject: Re: [TUHS] What was your "Aha, Unix!" moment? X-BeenThere: tuhs@minnie.tuhs.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: The Unix Heritage Society mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Ken Thompson via TUHS Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" On Mon, Oct 21, 2019 at 12:37:20PM +1000, Warren Toomey wrote: > 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 Aha indeed, Ken & Warren! chdir seems to be a syscall in 7 (sys4.c), its handling in sh mostly in xec.c, a real workout for the preprocessor ;) -- I love deadlines. I love the whooshing noise as they fly by.