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

segaloco via TUHS tuhs at tuhs.org
Sat Jun 3 09:04:16 AEST 2023

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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