I've assembled some notes from old manuals and other sources
on the formats used for on-disk file systems through the
Additional notes, comments on style, and whatnot are welcome.
(It may be sensible to send anything in the last two categories
directly to me, rather than to the whole list.)
I asked Jeff Korn (David Korn's son), who in turn asked David Korn who
confirmed that 'read -u' comes from ksh and that 'u' stands for 'unit'.
- Dan C.
Yes, indeed. He says:
*I added -u when I added co processes in the mid '80s. The u stands for
unit. It was command to talk about file descriptor unit at that time.*
On Tue, May 31, 2016 at 6:06 AM, Dan Cross <crossd(a)gmail.com> wrote:
> Hey, did your dad do `read -u`?
> ---------- Forwarded message ----------
> From: Doug McIlroy <doug(a)cs.dartmouth.edu>
> Date: Tue, May 31, 2016 at 3:27 AM
> Subject: [TUHS] etymology of read -u
> To: tuhs(a)minnie.tuhs.org
> What's the mnmonic significance, if any, of the u in
> the bash builtin read -u for reading from a specified
> file descriptor? Evidently both f and d had already been
> taken in analogy to usage in some other commands.
> The best I can think of is u as in "tape unit", which
> was common usage back in the days of READ INPUT TAPE 5.
> That would make it the work of an old timer, maybe Dave Korn?
What's the mnmonic significance, if any, of the u in
the bash builtin read -u for reading from a specified
file descriptor? Evidently both f and d had already been
taken in analogy to usage in some other commands.
The best I can think of is u as in "tape unit", which
was common usage back in the days of READ INPUT TAPE 5.
That would make it the work of an old timer, maybe Dave Korn?
> Now we are hoping to get the Living Computer Museum people to bring it up
on their real PDP-7.
Truly a fantastic prospect! The only Unix the museum has running is
on a 3B2--a curious byway perhaps, but of little historic interest.
The PDP-7 version would be a tremendous coup.
On Wed, May 04, 2016 at 12:44:15AM +0300, Diomidis Spinellis wrote:
> This would have found any code from the PDP-7 Unix that appeared in the
> First Edition. (I was hoping that some PDP-7 instruction sequences might be
> the same in PDP-11.)
> Unsurprisingly, nothing came out.
No, the instruction set is completely different. The PDP-11 ISA is a paradise
compared to the spartan PDP-7 ISA.
All, a status update on the PDP-7 Unix restoration project at
The system is pretty much complete now. We have as much of the original
code working as we can. We have rewritten things like the shell and some
other utilities (ls etc.). The ed editor and the native assembler both
work. We also have written a user-mode PDP-7 simulator to test things
and an assembler to make building things faster.
The system boots up under SimH with a filesystem and you can see what things
were like back in 1970.
One big missing utility is roff. As of today, I've written a compiler that
inputs a vaguely C-like language and outputs PDP-7 code. Using this, I've
compiled a minimalist roff which is enough to format man pages. This is
a separate project here: https://github.com/DoctorWkt/h-compiler
Now we are hoping to get the Living Computer Museum people to bring it up
on their real PDP-7. Unfortunately, it doesn't have a disk drive. The
expected solution is to build a disk simulator with an FPGA and SD card.
There is no time frame for this, but it is in the works.
Thanks go to Phil Budne and Robert Swierczek for all their hard work
in building and testing things, and also to Norman Wilson for supplying
scans of the original documents.
I had been lurking this list for long, this is my first post to this
I read with a lot of interest, an old Usenix paper by the late Richard
Stevens on a system called "Portals":
It explores a lot of ideas that found itself in Plan 9, like a
filesystem interface for sockets etc. Wondering if this survived in any
existing, so called "modern" Unix. I have always felt the need to have
something like this in Unix.