How to catch pkill signal in LINUX/C++?

[chrisben]

Hi,

I crontab a process kill like
pkill -9 MyApp

In my codes, I tried to catch the signal so I can ensure all destructors called.

The codes is like this


void handler(int s)
{
cout << "SIG " << s << endl;;

exit(0);
}

int main(int a, const char ** ac)
{
signal(SIGKILL, handler);
signal(SIGINT, handler);
while(true){
sleep(1);
}

It seems that I can only catch Ctrl-C event, but not the kill event.
Anything wrong in the codes?

Thanks

Chris

[jsmith]

SIGKILL cannot be caught, nor SIGSTOP / SIGCONT, according to POSIX.

[bigearsbilly]

nope, no can do.

be careful with pkill too.
it searches on a pattern, you may find yourself killing stuff you don't want to.
you should use -x at least really.
better still don't use it on a production system.

also some implementations (solaris?) have length limits on the string.


I've killed a load of important daemons on a production box with
injudicious pkills in my youth!

[chrisben]

Thanks for the reply. Here is my issues:

I usually use pkill to crontab autorestart my app and intra day restart (I could use -x as bigearsbilly suggested). My problem is that I found the destructors are not invoked in this case and my clean up work was not done properly.

I was thinking to use signal to catch the kill message so I can clean up something before it is down. Is there a better way to do it in LINUX?

Thanks

[jsmith]

Use another signal like SIGTERM instead. SIGTERM and SIGKILL essentially do the same thing, except
the kernel does not allow processes to catch or block SIGKILL.

EDIT: So pkill -SIGTERM <process-name>

[chrisben]

this works great! thanks a lot