Re: Commands run from functions don't exit cleanly on terminal close (SIGHUP)?

[Alan Pinstein <apinstein@mac.com>]

I need to make one clarification; the PPID ends up as 1 (orphaned) if no traps are installed; if the HUP trap is installed, the PPID remains correct, but it still doesn't exit.

Alan

On Oct 24, 2012, at 10:03 AM, Alan Pinstein wrote:

> I am having issues with ssh sessions not exiting when I closed the terminal window containing them.
> 
> I originally noticed this bug while using screen; I believe this bug/problem affects anyone that uses ssh/autossh/tmux/mxrvt/etc from inside a function. It causes screen to hang due to multiple concurrent connections that are orphaned on the client side.
> 
> I have reduced the problem down to whether or not the ssh command is executed directly in the shell, or from inside a function.
> 
> I isolated the issue from ssh as well; it seems that any command run from inside of a function doesn't cleanly exit when it receives a SIGHUP.
> 
> I managed to at least receive the signal before the child exits via TRAPS_ASYNC, but I can't figure out how to make the command die when the trap runs. I've tried "exit" and "return".
> 
> The function below reproduces the scenario easily.
> 
> willnotdie() {
>     echo 'try closing the terminal window while this runs (lasts 10s), notice that the php command is orphaned and does not die'
>     echo 'ps ax -o time,ppid,command | grep -v grep| grep "PPID\|php"'
>     echo 'if you run the PHP code in this script directly on the CLI, then it exists cleanly on terminal close'
> 
>     setopt LOCAL_TRAPS LOCAL_OPTIONS TRAPS_ASYNC
>     echo -n "" > ./sig
>     (date && echo START) >> ./sig
>     trap '(date && echo HUP && exit 1) >> ./sig' HUP
>     trap '(date && echo INT) >> ./sig' INT
>     php -r '$i = time() + 10; while (true) { if (time() > $i) break; }'
>     (date && echo DONE) >> ./sig
> }
> 
> # monitor the progress with this
> while (true) do
> ps ax -o time,ppid,command | grep -v grep| grep "PPID\|php"
> sleep 1
> done
> 
> I would appreciate any help.
> 
> Thanks in advance.
> 
> Alan