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Grex Garage Item 16: Ctrl-Z in PINE suspends process, how do I enter "fg" command?
Entered by herronjt on Wed Aug 17 13:11:13 UTC 2005:

I was in PINE last night, and accidentally hit Ctrl-Z.
My task was suspended and I was prompted to "enter fg command"
to continue or return, but I couldn't figure out how to enter
this command, so I was stuck.  I hung up and tried calling in
again, but then the 484-0513 number wasn't answering, and my
process 31245 was still running.  I dialed in to the 484-0512
number, and now my mailbox is READ-ONLY and the process is
still running, and 484-0513 still isn't answering.  How can
I avoid this accident in the future, and how can I enter this
"fg" command to resume, and How can I cancel process 31245?

10 responses total.

#1 of 10 by naftee on Wed Aug 17 13:23:24 2005:

Just type "fg" (without the quotes) at the prompt.
Like this :

bash-2.05b$ fg

To kill process 31245, type "kill -9 31245" (without the quotes) at the
prompt.
Like this :

bash-2.05b$ kill -9 31245

#2 of 10 by herronjt on Wed Aug 17 16:06:23 2005:

From Pico-Span I tried this:
Ok: !
$ kill -9 31245
/bin/sh: kill: 31245: No such process
So I hit Ctrl-D to return to Pico-Span.
I got the process # from within Pine.
The "who" command still shows the process,
but my mailbox is no longer locked.
Does the "fg" command work from within
the suspended Pine shell?  I tried entering
it right after I'd hit Ctrl-Z, but it
wouldn't accept it.  Do I need "!fg"?
I'm still confused, but running again.

#3 of 10 by rcurl on Wed Aug 17 16:36:36 2005:

Did you enter fg right at the new shell prompt? Always works for me....

#4 of 10 by herronjt on Thu Aug 18 00:07:31 2005:

Yep, I entered it immediately and it didn't work.
I don't remember what the reply message was, but
nothing happened, and I couldn't get back to Pine.
I couldn't get anywhere, I was stuck, so I hung up.
It seems to have taken down the 484-0513 modem, too,
because right after that it wasn't answering at all.

#5 of 10 by herronjt on Thu Aug 18 00:11:26 2005:

The "who" command still shows my process out there,
even though my mailbox has been released from READ-ONLY.
"who" gives:  herronjt  tty00  Aug 16 21:14
This was the process I tried to kill, but it still
shows out there, even though it relased my mailbox.

#6 of 10 by naftee on Thu Aug 18 02:26:29 2005:

 !who just shows if you're logged in.  Use !w if you want to see your current
process.
herronjt 00 -                Tue09PM 25:01 /usr/local/bin/bbs

Or perhaps
USER       PID %CPU %MEM   VSZ   RSS TT   STAT STARTED       TIME COMMAND
herronjt 31245  0.0  0.0     0     0 00  ZW+   -          0:00.00 (pine)

Weird.

#7 of 10 by davel on Thu Aug 18 15:16:28 2005:

kill -1   might be better than   kill -9
Or    kill -2   or    kill -3
(These are, respectively, SIGHUP, SIGQUIT, and SIGINT; -9 is SIGKILL.)
If the process in question has files in some kind of intermediate state,
SIGKILL should (assuming you're the owner of the process) force the thing
to just die, without any cleanup.  OTOH, the process can trap the others
and do something; what it will do, or whether it even will trap these
signals, varies from process to process.  One would hope that pine would
handle a hangup (SIGHUP) gracefully, closing things down, but I have no
experience with it.

#8 of 10 by herronjt on Thu Aug 18 15:42:17 2005:

I tired kill -1, and -2, and -3, and -9 again, and they all responded with
31245: No such process.  But clearly the process is still out there, even
though it has released my mailbox lock.  I believe this process is holding
the 484-0513 modem from answering.  I don't know how to kill it.  What was
the command that showed the Process ID above?  I got the number 31245 from
within Pine.  Maybe the Process ID is wrong???  It is truly weird!

#9 of 10 by naftee on Fri Aug 19 03:38:27 2005:

 !ps -uU herronjt

#10 of 10 by arthurp on Tue Oct 25 03:52:02 2005:

Probably what happened was the idle zapper killed your process which the
restored access to your mailbox, but because of a slight oddity in the
way parent and child processes communicate, your shell stayed longer
waiting for pine to respond which it couldn't because I bet the idle
zapper uses -9.  Therefore your shell, and the modem thought you were
still there, and your pine was still listed because it's parent wouldn't
let it die fully.  It was in what is known as a zombie state.  This is
only a problem in as far as the modem stayed active, and a pseudo
terminal and process table entry were kept.  Only the modem really
matters.  And all this would eventually fix itself at the next system
restart, or maybe with diligent staff help.  I'm sure it's fine by now
since all this was a while ago.

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