Reading stdout from pipe

[CashCow01]

Hi there,

I am trying to read stdout from a child process to parent using pipe. I am unable to do so. I would appreciate it if someone can point me in the right direction.

Here's my sample program for basic input output:

#include <stdio.h>

int main()
{
	char buffer[10];
	printf("first:\n");
	fscanf(stdin, "%s", buffer);
	FILE *fwriter;
	
	fwriter = fopen("aaa.txt", "w");
	fprintf(fwriter, "%s\n", buffer);
	fclose(fwriter);
	
	printf("b=%s\n", buffer);
	
	exit(0);
}

gcc simple.c -o sss

The program that calls fork():

#include <signal.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/wait.h>
#include <stdlib.h>
#include <string.h>

int main()
{
	char buffer[50];
	int fd[2], fd2[2];
	pipe(fd);
	pipe(fd2);
	pid_t pid = fork();
	if(pid == 0) {
		dup2(fd[0], STDIN_FILENO);
		close(fd[0]);
		close(fd[1]);
		
		dup2(fd2[1], STDOUT_FILENO);
		close(fd2[0]);
		close(fd2[1]);
		
		execlp("./sss", "./sss", 0);
	}
	else {
		close(fd2[1]);
		read(fd2[0], buffer, 50);
		printf(buffer);
		fgets(buffer, 50, stdin);
		/*sprintf(buffer, "%s\n", "doesNotMatter");*/
		close(fd[0]);
		write(fd[1], buffer, 50);
		close(fd[1]);
		
		printf("%s", buffer);
		close(fd2[0]);
		waitpid(pid, NULL, 0);
	}
	
	return 0;
}

gcc tp.c -o tp

The output of tp:

user1@xmac:~/pipe_test2$ ./tp
123qwe

^C
user1@xmac:~/pipe_test2$

What I would like : I want ./tp to print out "first:" before the prompt for input. Basically, it should emulate ./sss.

Thanks in advance.

[itCbitC]

There are lots of things wrong with the posted code. The child duplicates stdin to fd[0] and stdout to fd2[1] followed by immediately closing 'em. The first printf() in parent is wrong and the scheduler decides as to which process (parent or child) gets put on the cpu first. Though the scheduler's decision can be influenced by sleep()'ing in the appropriate process.