#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
 
void get_possible_error(int value, const char *);
void wait_process(pid_t, const char *);
 
int main() {
	pid_t child1_id=-1, child2_id=-1, child3_id=-1;
 
	child1_id = fork();
	get_possible_error(child1_id, "fork() child1_id");
	if(child1_id == 0) { /* hijo1 */
		/* sentencias... */
		printf("hijo1\n");
	} else { /* child1_id > 0 => padre */
		child2_id = fork();
		get_possible_error(child2_id, "fork() child2_id");
		if(child2_id == 0) { /* hijo2 */
			/* sentencias... */
			printf("hijo2\n");
		} else { /* padre */
			child3_id = fork();
			get_possible_error(child3_id, "fork() child3_id");
			if(child3_id == 0) { /* hijo 3 */
				/* sentencias... */
				printf("hijo3\n");
			}
			else { /* padre */
				wait_process(child1_id, "wait() child1");
				wait_process(child2_id, "wait() child2");
				wait_process(child3_id, "wait() child3");
			}
		}
	}
 
	return 0;
}
 
void get_possible_error(int value, const char *str) {
	if(value<0) {
		perror(str);
		exit(1);
	}
}
 
void wait_process(pid_t pid, const char *str) {
		pid = wait(&pid);
		get_possible_error(pid, str);
}