#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>

int main() {
	int f1 = open("read.txt", O_RDONLY);
	if (f1 < 0) {
		perror("open read.txt");
		return 1;
	}

	int f2 = open("write.txt", O_CREAT | O_WRONLY | O_TRUNC, 0755);
	if (f2 < 0) {
		perror("open write.txt");
		return 1;
	}

	pid_t fpid = fork();
	if (fpid < 0) {
		perror("fork");
		return 2;
	}

	if (fpid == 0) { // child
		for (int i = 0; i < 5; i++) {
			sleep(2);
			write(f2, "abc", 3);
		}
	}
	else {
		char buff[3];
		for (int i = 0; i < 5; i++) {
			read(f1, buff, 3);
			write(f2, buff, 3);
			sleep(1);
		}
	}
}