#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <wait.h>
#include <errno.h>

void run(void)
{
	int pid;
	while ((pid = fork()) == -1)
		sleep(1800);
	if (!pid) {
		char * const av[4] = {"sh", "-c", "./myscript.rb >& log.`date '+%m%d-%H%M'`", NULL};
		execv("/bin/sh", av);
		exit(1);
	}
	while (waitpid(pid, 0, 0) == -1 && errno == EINTR);
}

int main(void)
{
	int pid = fork();
	if (pid > 0)
		return 0;
	close(0);
	close(1);
	close(2);
	setsid();
	
	for (;;) {
		run();
		
		int fd;
		fd = open("delay", O_RDONLY);
		if (fd == -1) {
			sleep(10*3600);
			continue;
		}
		
		int delay = 0;
		char c;
		while (read(fd, &c, 1) == 1) {
			if (c < '0' || c > '9')
				break;
			delay *= 10;
			delay += c - '0';
		}
		close(fd);

		sleep(delay);
	}
	return 0;
}