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Old 03-02-2011, 04:34 PM   #1
Richard Rahl
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Shutting down of daemons during Ubuntu shutdown


Hello,

I'm interested in finding out, specifically, what causes daemon's to be shutdown when I shutdown Ubuntu?

I'm use Ubuntu which is why I'm posting here, but I suppose this knowledge could apply to other Disto's too.

Perhaps I'm better off to explain with an example:

I wrote a C++ that queries a Mysql database. I want it to run every time the computer is shutdown.

I've verified the program works fine, and I've verified that I can run a program on shutdown of the computer by putting it in /etc/rc0.d

The problem is that by the time rc0.d runs my program, mysql has already been shutoff, and it can't connect.

So what I'm wondering is, is there a script or something at a higher level that goes around turning things like daemons as the System shutdowns, but before any of the scripts in rc0.d are run? (It doesn't look like anything in here is shutting down mysql). Something that actually calls mysql shutdown?

If so, I'm hoping someone could point me to it and I can add my program to be run before mysql shuts down.

Otherwise, I might end up having to get the source code compile by own /sbin/shutdown and tweak it from there. Granted I might end up doing this anyway because there's more stuff I want to customize during shutdown (e.g. abort it under certain conditions), but I'm hoping not to go that far just yet.

Any suggestions, please let me know. Thanks!
 
Old 03-02-2011, 07:25 PM   #2
michaelk
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In a nutshell the files in rc0.d are links to the actual scripts in /etc/init.d. The links start with either a KXX or SXX. The K i.e kill run first in order from 99 - 1 and stop the associated process. The SXX i.e. start runs second in numerical and will start the associated process. If you configure your script to start in runlevel 0 with a value of 1 (filename S01myscript) it will run first before anything else shuts down.

http://www.debuntu.org/how-to-manage...th-update-rc.d
https://help.ubuntu.com/community/UbuntuBootupHowto

sendsigs is the global command to shut down running processes.

Last edited by michaelk; 03-02-2011 at 07:31 PM.
 
Old 03-02-2011, 08:19 PM   #3
Richard Rahl
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Quote:
Originally Posted by michaelk View Post
In a nutshell the files in rc0.d are links to the actual scripts in /etc/init.d. The links start with either a KXX or SXX. The K i.e kill run first in order from 99 - 1 and stop the associated process. The SXX i.e. start runs second in numerical and will start the associated process. If you configure your script to start in runlevel 0 with a value of 1 (filename S01myscript) it will run first before anything else shuts down.

http://www.debuntu.org/how-to-manage...th-update-rc.d
https://help.ubuntu.com/community/UbuntuBootupHowto

sendsigs is the global command to shut down running processes.
Hi there, thanks for the response.

I did know about the symlinks and the run levels. Unfortunately even linking my script as S01script name doesn't work. As a test, one of the things the script does is append the output of "ps -ef | grep mysql" to a file in my Home directory. When I check the file after rebooting, all I see is the grep process, making it clear that mysqld isn't running when the script runs.

Your post did give me another idea though. Instead of using the Sxx scripts, I tried using a Kxx script to run my program instead.

Likewise, I did the same test by appending the output "ps -ef | grep mysql" to a file. This time, I do indeed see the mysqld process is still running when the KXXscript runs. Great. Unfortunately, my program still can't connect.

It connects fine when the system isn't shutting down. So there must be something else preventing it from connecting when being run from the KXX script, even though mysqld is still running at the point. I'll need to investigate this further, but in the meantime if anyone has any other suggestions let me know.

Thanks!
 
  


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