Re: [Help-bash] backgrounding a process sends it into a tailspin

[Chet Ramey]

On 9/12/12 11:06 PM, Cook, Rich wrote:

>> I can't reproduce this on Mac OS X, using bash-3.2 to bash-4.2 and
>> gnuplot-4.whatever-fink-gives-you, or on Fedora 15, using bash-4.2 and
>> gnuplot-4.4.  I used the orignal script without the imgtrack stuff.
>> It doesn't matter whether I start the script in the background using `&'
>> or in the foreground and use ^Z.  Even ^Z/bg doesn't cause any weird
>> behavior.
>>
>> Maybe we could get back to basics: system type, OS version, bash version,
>> gnuplot version.
> 
> OK, sure, great, thanks
> Here is some info: 
> address@hidden (lclocal.el6): uname -a
> Linux rzgpu2 2.6.32-220.23.1.1chaos.ch5.x86_64 #1 SMP Tue Jun 19 17:16:17 PDT 
> 2012 x86_64 x86_64 x86_64 GNU/Linux

OK, I can reproduce this when I ^Z gnuplot and put it into the background
using `bg', but only on Fedora.  In a way, that's to be expected, since
you're attempting to run it without a controlling terminal and all, but it
doesn't happen on Mac OS X with bash-4.2.37 and Gnuplot 4.6.  It does
happen on Fedora 15 with bash-4.2.10 and Gnuplot 4.4.2.  The MacOS X
behavior is correct: the process should stop.  There is something screwy
with Gnuplot's signal handling.  I'll take another look this weekend if I
have time.

Chet

-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, ITS, CWRU    address@hidden    http://cnswww.cns.cwru.edu/~chet/