[TUHS] CB-UNIX dsw(1l) Page from PDP-7?

Marc Donner marc.donner at gmail.com
Sat Jun 3 22:59:35 AEST 2023

Wow.  I’m impressed … that pdf is clearly of an nth generation photocopy.
What contrast ratio?

More seriously, this is a delightful proof point that some cruft is really

Your document archaeology work is entertaining and instructive.  Thank you!


On Fri, Jun 2, 2023 at 7:04 PM segaloco via TUHS <tuhs at tuhs.org> wrote:

> While performing my CB-UNIX 2.3 manual separation, among the many curious
> things I came across was this manual page:
> https://www.tuhs.org/Archive/Distributions/USDL/CB_Unix/man/man1/dsw.1l.pdf
> The dsw(I) pages I've seen in the various UNIX manuals are all for the
> interactive delete utility, but make brief mention of the history of the
> command being amusing.  I've seen some communication on the matter of the
> years here, but had never come across a manual page for the former version
> of dsw.
> In the linked page up there is the actual "delete from switches" version
> of dsw.  What I find particularly interesting is that the footer indicates
> this was printed 8/11/81, but likewise indicates the command is "PDP-7
> local".
> This raises a couple of questions:
> - Did Columbus ever touch PDP-7 UNIX?
> - Did dsw(I) as "delete from switches" ever make it to PDP-11 UNIX?  Even
> the V1 manual lists the "delete interactively" utility, not this.
> - If neither are true, that begs the question of where this page came
> from, if there was ever a formalized PDP-7 manual that it would've
> descended from or not, etc.
> Finally, this page plainly spells out the history of the command in the
> bugs section:
> "This command was written in 2 minutes to delete a particular file that
> managed to get an 0200 bit in its name.  It should work by printing the
> name of each file in a specified directory and requestion a 'y' or 'n'
> answer.  Better, it should be an option of rm(1).  The name is mnemonic,
> but likely to cause trouble in the future."
> So the first bug is eventually mitigated by transforming this into the
> more familiar dsw.  I can't say what the latter means, whether it's a
> concern of "dsw" colliding with some reserved word eventually or is more
> poking fun at the other folk etymology of "delete s__t work".
> In any case, I hadn't seen the etymology explained to this degree in the
> mailing list references I found while searching around, so figured I'd
> share this analysis.
> - Matt G.
> P.S. There is mention here that Dennis Ritchie shared the original dsw
> manpage at some point
> https://www.tuhs.org/pipermail/tuhs/1999-November/001203.html however the
> link in question appears to be dead.  In any case, the source for the PDP-7
> version is in that email if anyone wants to look at it, although looks to
> be the same as what is in the archive.
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