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Re: HUP doesn't send to processes when logout

2008/12/30, Jerry Feldman <gaf blu org>:
> On 12/29/2008 10:05 AM, 平天韩 wrote:
>> hi,
>> It seems that when I logout from the console, the background process
>> doesn't get HUP signal:
>> { trap "echo Ignore HUP >>/tmp/trap.out" 1; while sleep 3;do echo
>> hello >>/tmp/hello.txt;done; }&
>> And it seems it will become a daemon and run forever until rebooting.
>> Is this correct? Why it didn't get HUP signal?
>> Thanks!
> Are you running this from a terminal window?

I am running this in tty2, a console. I just type those into the
console and run it, then logout.

> Are you possibly setting nohup in your environment.

It seems it is. But how?

> Are you typing the above commands directly? What happens if you place
> these into a script and run the script in the background?
> There are a number of things that can cause a shell script to ignore the
> HUP signal. I tested this as a script on an Ubuntu laptop, and it
> behaved the same as yours:
> The process remained. So the issue is not that exiting the parent
> process (GNOME Term) or logging out of GNOME fails to issue a HUP, it is
> that the process itself ignores the HUP signal since I sent a "kill -HUP
> <pid>" to the process.
> If you simply send the HUP signal, you will see that "Ignore HUP" will
> appear in /tmp/trap.out".
I have the same results with you.

> The signal(1) command is probably the culprit, though the man pages are
> vague.
I suspect of that maybe the logout doesn't send out HUP to these
background processes?
> --
> Jerry Feldman <gaf blu org>
> Boston Linux and Unix
> PGP key id: 537C5846
> PGP Key fingerprint: 3D1B 8377 A3C0 A5F2 ECBB  CA3B 4607 4319 537C 5846

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