> > ... I do all my editing on my Macintosh, then copy&paste
> > across dialup modem to Unix, the only place where CMUCL is
> > available for me to use, where I do all line-by-line testing, all
> > full-function testing, and all R&D testing. When I need to restart
> > Lisp, because I lost my dialup connection or it's another day and
> > I'm logging in again,
> From: Logan Shaw <lshaw-use...@[EMAIL PROTECTED]
>
> Assuming you are doing everything at the terminal
I don't know what you mean by "terminal". My Macintosh, as any
Macintosh since they were first invented, has multiple windows on
screen, overlapping so that I can select a mostly-hidden window by
clicking on some visible corner of it. One window is the VT100
terminal-emulator, others are Finder or McSink. All my editing is
in various McSink windows, not the one VT100 terminal-emulator
window. So it's not correct to say that everything I do is at the
(VT100) terminal, since most typing is done at some other window.
> which is a fair assumption if you're using dialup
I don't know what you mean by "dialup". When most people nowadays
talk about "dialup", they mean PPP or SLIP or DSL, not VT100. I
don't have anything available except VT100 here. VT100 emulator on
my Mac goes directly through my modem then through voice-grade
phone connection to modem at ISP which then goes through some
TELNET-like digital link to the actual shell machine.
> try out the "screen" program under Unix.
Several people have suggested that over the past several years, but
it has been too much of a nuisance to even consider it, until last
night. Normally the modem loses carrier just a few times per day,
some days not at all for ten hours I'm dialed in, so it's only a
minor inconvenience to have to re-dial and re-establish whatever I
was doing at the time. But last night things got **HORRIBLE**, with
modem hanging up on the average every five minutes, all evening and
through the night until I went to bed. I finally decided times were
desperate enough to try screen. (I didn't see your article until
after I got up this morning, Saturday, so your article was a
coincidence!) But every time I tried to 'man screen', the modem
would hang up before I could get to the im****tant commands I
needed. Finally the modem stayed connected enough to see page 5
where said
If you're impatient and want to get started without doing
a lot more reading, you should remember this one command:
"C-a ?". Typing these two characters will display a list
of the available screen commands and their bindings.
before it disconnected again. So the next time I dialed in I said
'screen' and then tried that list-commands command, but it was
inscrutable, so I had to go back to the manual to see more, except
it disconnected again, so I was back to trying over and over to
display enough of the manual to see how to attach to my
disconnected screen. It looked like -d -r was closest to what I
wanted, even though -D -R was the author's favorite. But I read
further and decided to try just -r by itself, saving -d -r for the
case where -r didn't work because the old screen had failed to
become detached when the modem lost carrier. It had taken a half
hour of re-dialings over-and-over just to find out about C-a ? and
start screen the first time, and it took another half hour
of re-dialings over-and-over before I could finally see that info
about -r etc. and decide what to try, and -r worked fine.
So for the rest of the night I was re-dialing over and over, about
every 2-5 minutes, it was **horribly bad**, and each time I'd
compose one line of code on my Mac while I was disconnected and
then re-dial then screeen -r then copy&paste the one line of code
into screen-CMUCL before the modem would disconnect again.
So now I'm using screen to protect myself from lost of context when
modem loses carrier. Already this morning, modem lost carrier once
while I was composing the previous followup (to moi, the nice
person who converted PDF text to plain ASCII text and posted it),
but so-far it hasn't dropped carrier again while posting that and
composing this new followup to you. So the modems seem to be in
halfway decent shape now. But since I've made the investment to
learn how to use screen, I might continue using it.
One thing about it I don't like: Last night, after I finally got my
new test routine written and debugged and running, where it was
spewing out lots of text (with SLEEPs every so often to avoid
overflowing modem buffers), I was letting it run a few minutes,
then ctrl-C to interrupt it to a breakpoint, then scrolling the
VT100 emulator back to copy&paste the stuff that had gone
off-screen during that batch, then starting it again then ctrl-C to
copy&paste. If the modem lost carrier while it was stopped in a
breakpoint, I'd just finish my batch of copy&paste before
re-dialing. But one time the modem lost carrier while my program
was spewing out, before I could interrupt it, and by the time I
came back it had spewed out much more than a screenful, which is
*not* saved by screen, so I lost all that output and had to stop
the whole process at that point. I spent a half hour browsing the
manual, interrupted by lost modem about every 2-5 minutes, and
never did find any way to scroll back within screen to see anything
that had scrolled off-screen while the modem was disconnected. I
saw some command for starting some mode that saves stuff that
scrolled off-screen, but I couldn't find any way to scroll back
even after that mode had been entered.
> It's a terminal emulator within a terminal.
I'm not sure that makes any sense, unless by "terminal" you mean a
Unix termcap sort of thing. I guess that's what you mean.
> It sup****ts multiple sessions, which is to say that it can
> emulate more than one terminal at a time and let you switch between
> them.
For my purpose, that isn't necessary. I'm content to ctrl-Z and
switch jobs just as I did before starting to use screen.
> The reason it's interesting in your situation is that it has
> essentially a client-server architecture. When your modem hangs
> up, the client will die, but the server (which maintains the state
> of the emulated terminals -- and thus all the programs running
> within them) remains, and you can reattach to it with "screen -r".
*now* you tell me "screen -r"!! Last night it would have taken me
three hours of re-dialing to find your article, and I might never
have found it at all because Google Groups would need to be
re-started from scratch each time the modem lost carrier, and I
wouldn't be able to remember where I left off, that's even *if* I
could somehow magically read your mind that you had posted a
suggestion to use screen and you had included "screen -r" within
it. It took only an hour to find the info via repeatedly re-dialing
and re-starting 'man screen', which turned out to be faster and
less frustrating. But thanks for trying. If I had seen your article
just *before* the modem went totally bad, and if it had been fresh in
my mind when the modem did go bad, it would have saved me a half
hour.
Hmmm, still dialed in, modem hasn't disconnected again the whole
time I've been composing this followup, much better than last night!!
> Obviously, you cannot use it to keep your programs alive forever
> because there are other limits,
Yeah, like the admin here doesn't condone tying up resources that
are not being used for long period of time. It's explicitly
forbidden for PPP users to run a program that automatically
transmits something through the connection at regular intervals to
keep it from timing out the connection and needing (automatic)
re-dial. I think if I were to keep a screen active when I go to bed
at night, or when I go away from home, that would be frouned on
too. So last night, when modem crapped out just as I was getting
ready to go to bed, before I could shut down screen, I deliberately
re-dialed just to properly shut down screen to avoid having it sit
there while I was sleeping.
*** At this point in my composing followup, modem crapped out again ***
Re-dialing at 10:50 PDT ... ISP's dialup phone line is busy, trying
again ... not busy, establi****ng 19200 bps modem, logging in,
reattaching screen, not 10:52 PDT.
> Drop to the command line on the Mac and use "rsync".
**what** command line???
Macintosh System 7.5.5 doesn't have a command line!!
None of the applications that I've ever used on a Mac have command line
either!
> This assumes you have TCP/IP connectivity between the Mac and the
> Unix machine
No I don't. Didn't you read the part about using VT100 dialup into
Unix shell?? Please read this FYI:
<http://www.rawbw.com/~rem/NewPub/mySituation.html>
> but that can be accomplished over dialup.
The VT100 emulator understands **only** VT100. AFAIK there's no way
to run rsync over VT100 terminal emulator. Only Kermit and Zterm
work over it. And Kermit only half works, because the Kermit on
FreeBSD Unix has a bug: It fails to convert between DOS and Unix
newlines. So before I download any file via Kermit, I need to go
into Emacs to change all newlines to (*) CR-LF combinations, and
after I upload any file from Mac I need to create a one-line
Unix-format file then append the DOS-format uploaded file after it
then go into Emacs which recognizes to change all but the first
newline from CR-LF back to just LF. Copy&paste directly across
modems is much more convenient, so I use Kermit only when I need to
upload or download a really big file that would be too much trouble
to chop into 30k pieces or copy&paste. But in any case, I'm pretty
sure Kermit can't do rsync. And zterm doesn't even exist on FreeBSD
Unix. (man and whereis both turn up empty.)
(*) MODEM LOST CARRIER AGAIN AT 10:57, REDIALING, BACK ON AT 10:59
> Use "rsync -a localdir remotehost:remotedir", for example.
If I had a machine that could do it I would, but I don't.
|
