When did the Unix filesystem add the semantics for "files with holes" (large,
sparse files)?
Just an idle question that was sparked by a conversation I had today.
Erik <fair(a)clock.org>
The more I think about this, the more I'm sure I'm barking up the wrong
tree...
>From bits and pieces I've been able to recall, the thing I am looking for
was not about Unix - it was about TOPS-20. It was a timeline of the
system bootstrap activities from power-on to the point where users could
log in. I still don't remember where I found it originally, but at least
now I'm pretty sure I've been looking in all the wrong places... I
believe it originated at CMU, but I don't know for sure that that's where
I originally located it.
The actual problem I'm trying to solve is, at this point in my
professional career, I'm starting to interact with a lot of people (even
experienced software developers) who just have no clue of what has to
happen to get a computer from the point of "power-on" to the point where
they can actually use it to do things. This makes me sad... So, I'm
looking for something that I can point these people to that could clue
them in... I think the whole bootstrap process is useful to understand
for a lot of reasons, partly because it makes you think about all the
little fiddly details that have to be attended to to make the computer do
what you want - when I was first learning about this, I remember being
particularly fascinated by what had to happen to prepare for that moment
at which you turn on the MMU, to make sure that the system continues
executing in a place you expect it to, in the right processor mode. I
know most people that I interact with are using Linux or Windows on
Intel-architecture machines, but the boot process for Unix on the PDP-10
or VAX (or even TOPS-20 on the PDP-10) I thought would be a much simpler
thing to understand. Though maybe that's the wrong thought process, maybe
I should just find something related to Linux that is comparable (even
though I think it's more complicated).
While searching, I also came across a decent presentation by a friend of
mine who teaches at CMU, and discusses hardware that people probably
actually work with right now, but I think it would be best consumed along
with the actual lecture that it goes with.
http://www.cs.cmu.edu/~410-f08/lectures/L20_Bootstrap.pdf
Maybe I'll find what I was originally looking for at some point, but after
spinning on this for most of the day, I don't think it's related to
Unix...
--Pat.
This thread brings to mind a wonderful saying which I just saw in another forum:
"A wise man speaks when he feels he has something to say - a fool speaks when
he feels he has to say something."
And to reply in advance to the 'but I did't realize so many other people had
sent in replies' - try scanning your emailbox before replying to messages to a
large list.
S/N is to be hallowed.
Noel
This book can apparently be "borrowed" from the Internet Archive. I'm not
sure how they do that, haven't tried to, I just see it says you need to
log in to borrow the book for 14 days.
https://archive.org/details/unixprimerplus00wait
--Pat.
OK, something that's not a ping :-)
I'm trying to track down the author of a cartoon that I'd like to use
in my book so that I can try to get permission. Last one that I need!
It's a cartoon that I only have on paper and don't know where it came
from. It has two frames, then and now, the first with a bunch of
cavemen grunting awk, grep, mkdir, yank, the second with a bunch of
people sitting at computers uttering the same.
I recently stumbled upon something that said that these were in a book
called "UNIX Primer PLUS". Anybody have a copy of that? If so, can
you please check to see if that's the original or whether they got it
from somewhere else?
Thanks,
Jon
On 04/10/19 09:59, arnold(a)skeeve.com wrote:
> Nemo <cym224(a)gmail.com> wrote:
>> On 10/04/2019, Warren Toomey <wkt(a)tuhs.org> wrote:
>>> Just checking you are all still out there :-) Cheers, Warren
>> Well, this is not "Forever September"? #6-) I just finished reading a
>> fascinating article on Inferno and was most amused by the comment in
>> Rob Pike's biblio note at the end. N.
> So, please share article link and comment with the list? Thanks, Arnold
Apologies -- I found it here:
https://ieeexplore.ieee.org/document/6772868/ Bell Labs Tech. J., Vol.
2, Iss. 1, 1997 (or here
https://onlinelibrary.wiley.com/doi/pdf/10.1002/bltj.2028 but there must
an open version available by now).
Pike wrote: "He has never written a program that uses cursor addressing."
N.
So, a while back I mentioned that I'd done tweaked versions of 'cp', 'mv',
'chmod' etc for V6 which retained the original modified date of a file (when
the actual contents were not changed). I had some requests for those versions,
which I have finally got around to checking and uploading (along with 'mvall',
which for some reason V6 didn't have). I've added them to a couple of my V6
pages:
http://www.chiappa.net/~jnc/tech/V6Unix.html#mvallhttp://www.chiappa.net/~jnc/tech/ImprovingV6.html#FileWrite
Note (per the page) that the latter group all require the smdate() system
call, which was commented out in 'vanilla' V6 (because using it confused the
backup system); the page gives instructions on how to turn it back on.
Noel