linux pipe fork

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

int main() {
    int pipefd[2];
    pid_t pid;
    char buffer[256];

    if (pipe(pipefd) == -1) {
        perror("pipe");
        exit(EXIT_FAILURE);
    }

    pid = fork();
    if (pid == -1) {
        perror("fork");
        exit(EXIT_FAILURE);
    } else if (pid == 0) { // 子进程
        close(pipefd[1]); // 关闭写端
        read(pipefd[0], buffer, sizeof(buffer));
        printf("Child received: %s\n", buffer);
        close(pipefd[0]);
    } else { // 父进程
        close(pipefd[0]); // 关闭读端
        write(pipefd[1], "Hello from parent!", 17);
        close(pipefd[1]);
    }

    return 0;
}

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

void child_process() {
    printf("Child process: PID = %d\n", getpid());
}

void parent_process(pid_t pid) {
    printf("Parent process: Child PID = %d\n", pid);
}

int main() {
    pid_t pid = fork();

    if (pid == -1) {
        perror("fork");
        exit(EXIT_FAILURE);
    } else if (pid == 0) {
        child_process();
    } else {
        parent_process(pid);
    }

    return 0;
}