daemon_c.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <stdbool.h>
#include <sys/types.h>
#include <sys/stat.h>

int main(int argc, char* argv[])
{
  pid_t pid, sid;
  int status;

  pid = fork();
  if (pid < 0)
    exit(EXIT_SUCCESS);
  if (pid > 0)
    exit(EXIT_SUCCESS);

  umask(0);

  sid = setsid();
  if (sid<0)
    exit(EXIT_FAILURE);

  if (chdir("/") < 0)
    exit(EXIT_FAILURE);

  close(STDIN_FILENO);
  close(STDOUT_FILENO);
  close(STDERR_FILENO);

  while(true)
    {
      sleep(30);
      status = system("service mysql stop");
      if (status < 0)
	{
	   system("service mysql start");
	}
    }

  exit(EXIT_SUCCESS);
}