Question

I am currently using a script to call pkill to terminate my C++ program.
However i noticed that the destructors were not called from my traces when using pkill.

Is there another good way that i can exit the program gracefully?
pkill seems kind of untidy and some logs in the buffer do not get recorded. I’d like to be able to flush on my fstream and to close all resources programatically (instead of relying on the O/S to clean up my mess).

The application runs 24/7 without any problem, the only time i want to stop it is during maintenance. The application does not have any user interface for me to type exit.

Answer 1

You do it by defining a signal handler for SIGTERM along these lines:

Somewhere in your include block:

#include <signal.h>
#include <stdio.h>

Yes, we’re doing i C style!

Somewhere in the initialization part of your code:

signal (SIGTERM, handler);

and then define the signal handlers code (flush everything, etc):

void handler(int num) 
{
  // we might use this handler for many signals
  switch (num)
  {
    case SIGTERM:
      // clean up code.
      break;
  }
}

Now when you run pkill <app>, where <app> is the name of the executable, the code for handler() will run.

Without switches, the default SIGTERM signal will be sent to the application. Should you choose to use a different signal you would have to make sure you send the same signal as you “catch” in the handler().

Relevant information can be found by man 7 signal and of course, man kill.