[SOLVED] Killing subsequent child process upon parent receiving a signal

grail · 07-13-2011, 08:50 AM

Well firstly I would probably suggest you look at pkill to replace your pgrep, sed, xargs line.

As for the extra output, it may be because it is not part of the pgid and hence throws an unrelated error??

ta0kira · 07-13-2011, 09:09 AM

Quote:

Originally Posted by acc_Wk

Thanks for this tip!! Indeed this is a much better way to kill all my processes by way of group id.. But can you please elaborate on what exaclty "jobs -x kill %%" does ?
As for the disadvantages of using kill -9, I agree, but in my case, I dont want to do any clean up in processes B&C (which i'm SIGKILLing) and dont have a handler for them.. So if I reach the handler of A immediately after a signal arrival, I would like to kill it's children and do clean up pertaining to A...

You can get more information with help jobs. The jobs built-in operates on background jobs, and -x executes a command with the pid substituted for %%. It's similar to -exec with find.

I think you misunderstand the scope of exit handlers. When you SIGKILL a shell script you deny the shell its proper exit procedures. Even though your script doesn't need cleanup, you don't know what bash needs to do to exit gracefully.
Kevin Barry

ta0kira · 07-13-2011, 09:31 AM

Quote:

Originally Posted by acc_Wk

The portion in bold removes all messages except the one below:

Code:

/etc/opt/common.sh: line 241:  5633 Killed                  $cmd
      5634                       | tee -a $log_file

I suspect something to do with tee command is causing the problem.. Any idea?

Thanks a lot for all the help!!

This is job control output printed directly to the terminal.
Kevin Barry

ambrop7 · 07-14-2011, 06:54 AM

I highly recommend that you use a programming language other than Bash for that. Shell scripts are terrible for event-driven programming (which this is - waiting for events (signals, child terminated) and responding to events).

I've developed a comprehensive framework for event-driven programming in C, focused on networking, as part of my open-source BadVPN project. It supports management of child processes. I even have a nice example.

sundialsvcs · 07-14-2011, 08:10 AM

Following-on to ambrop7's post ... always look first for "prior art." Choose a "real" programming language ... I have become quite fond of Perl (specifically because of its vast CPAN library), but you have a half-dozen or more to choose from. Then, look for an existing framework that you can simply grab off the shelf and use. While programming is (sometimes) great fun, remember this rune:

Actum Ne Agas: "do not do a thing already done."