On Thu, Jul 31, 2008 at 11:11 PM, Paul Smith <psmith@aconex.com> wrote:
>>
>> But if for some reason, I need to start the app from an SSH session
>> (putty), the application sometimes dies after I log out. Sometimes
>> right away, sometimes after some time has passed. Nothing about
>> interesting is written to the log file. Normally the app makes log
>> entries when it shuts down cleanly. The process is just gone. This did
>> not happen prior to implementing log4j. Previously, the app wrote to a
>> pre-configured file and to System.out. Closing an SSH session had no
>> ill effects.
>>
>
> This is not really a logging question per-se, but I feel for you.  Unix
> process can die after the user shell that created them exits.  To be honest
> there doesn't appear to be a hard and fast rule as to this behaviour, but
> I'm quite confident it has nothing to do with log4j.  the 'nohup' unix
> command was originally designed for this purpose, but there's an even better
> way.
>
> Since you are launching a process that you want to stick around regardless
> of the connectivity of the shell process that launches it you should
> consider using the 'screen' application built into most *nix's.
>
> host> screen -S "Some Logical Name"
> host> /home/me/launchApp.sh
> ...
> .
> ..
>
> You can exit that terminal session at any time and it'll be safe from a hang
> up.  Even better, you can relogin and do:
>
> host> screen -ls
> There is a screen on:
>        23608.Some Logical Name (Attached)
> 1 Socket in /tmp/uscreens/S-psmith.
>
> you can then reconnect by:
>
> host> screen -r 23608
>
> or via other options (by name etc).
>
> 'screen' is fantastic when you're dealing with remote servers that you have
> problematic connections to (say, if they're on the other side of the world,
> which for me in Australia, is basically everything! :) ).  You can launch
> critical scripts knowing that a tcp disconnect will not cause any harm and
> you can come back to it later, even from a completely different computer.
>
> The authors of  'screen'  are definitely on my 'List of People To Buy Beers
> For".

Well I'm not convinced that this is completely unrelated to log4j.
This set of apps has run for 8 years in one form or another and has
been scripted to survive a logout. Now, with no changes except the
introduction of log4j, the behavior has changed.

In any case, I appreciate the pointer to screen. I will check it out.

-- 
Jeff

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