Application Cleanup on Shutdown

[whatisron]

I'm trying to do some cleanup (write open files) when Linux shuts down. I thought the right method would be to trap SIGTERM and do the necessary processing. Here's my sample code:

#include <stdio.h> // for File I/O
#include <signal.h> // for signals
#include <unistd.h> // for sleep()

void handler(int signal)
{
	FILE *out=fopen("test.txt","at");
	if (out)
	{
		fprintf(out,"got %d\n",signal);
		fclose(out);
	}
}

int main()
{
	signal(SIGTERM,handler);
	signal(SIGINT,handler);
	sleep(30);
}

When I run this, and press Ctrl-C, it write "got 2" to test.txt. However, if I logout/reboot, nothing is written to the file.

Any help or ideas would be appreciated!

-Ron

[Rubberman]

What is your working directory when you create this file? If in /tmp then it will be (possibly) nuked on reboot. Anyway, what happens if you do the fopen() call in main and just print/flush in the handler? IE,

#include <stdio.h> // for File I/O
#include <signal.h> // for signals
#include <unistd.h> // for sleep()

FILE* out = 0;
void handler(int signal)
{
	if (out)
	{
		fprintf(out,"got %d\n",signal);
		fflush(out);
	}
}

int main()
{
	out=fopen("test.txt","at");
	signal(SIGTERM,handler);
	signal(SIGINT,handler);
	sleep(30);
/* No need to close 'out' as it will be closed automatically. */
}

[Rubberman]

In any case, if you aren't placing this file in /tmp, then perhaps the OS is not sync'ing the discs when you reboot. It should, but I don't know what's been done to your system configuration. One of the shutdown scripts might have been altered to change that behavior. So, if my example code doesn't work when you reboot, try executing a specific system sync command before you reboot. If that works, then you know your OS is not functioning properly at shutdown.