C：如何在 execv 之前通过管道将值从子进程传递到父进程？

如何解决C：如何在 execv 之前通过管道将值从子进程传递到父进程？

在开始之前，我只想说这是我的一个学校作业。我真的快要完成了，除了好吧，因为我在这里，很明显，我遇到了一个问题:(。

首先我会解释我的任务想要什么：
作业要我用 C 创建一个命令行程序，允许用户输入 N 个 /bin/ 命令（例如 > /bin/ps /bin/ls "/bin/which gcc"）。一旦用户输入命令并按下回车键，父进程（父进程就是程序）将创建N个子进程（即输入的/bin/个命令数=父进程将创建的子进程数））。每个孩子将运行 N 个命令之一。所有子进程将同时运行，父进程等待每个子进程终止。
一旦子进程终止，父进程将打印命令是否成功执行（例如 "Command /bin/ps has completed successfully" 或 "Command /bin/ps has not completed successfully"），一旦所有子进程终止，父进程将打印 "All done,bye!"

问题：
所以我设法让我的子进程同时运行，唯一的问题是我不确定如何从子进程通过管道传递命令的值（如 /bin/ps 或 /bin/which gcc）到父进程打印出成功或不成功的消息。我试过将写管道放在我的 execv 上方，这允许我通过管道传输我想要的东西，但 execv 不会输出任何内容，我不能将管道代码放在我的 execv 下方，因为在那个情况，那么虽然我的 execv 输出会显示，但我的管道不会。我确实认为这可能是由于 close(1) 造成的，但将其注释掉并没有改变结果。所以我想要实现的是这样的：

> /bin/ls "/bin/which gcc" /bin/domainname /bin/fake_command
Output:
/usr/bin/gcc
localdomain
Command /bin/which gcc has completed successfully
Command /bin/domainname has completed successfully
a.txt b.c
Command /bin/ls has completed successfully
Command /bin/fake_command has not completed successfully
All done,bye!
>

但现在，我得到：

> /bin/ls "/bin/which gcc" /bin/domainname /bin/fake_command
Output:
Command /bin/which gcc has completed successfully
Command /bin/domainname has completed successfully
Command /bin/ls has completed successfully
Command /bin/fake_command has not completed successfully
>

如您所见，execv 命令的 /bin/ 输出未显示在输出中。

我已经尝试为与我面临类似问题的人进行搜索，但他们的解决方案都没有对我有用，这就是我在这里问的原因。如果您有任何不清楚的地方，请告诉我，我会尽力解释。

代码：
q1.c

#include "q1.h"

int main(int argc,char *argv[])
{
    int
            child_status,pipe_array[2];

    pid_t child;

    char *success_or_fail;

    char *msg_buffer = malloc(CHAR_MAX);
    if (msg_buffer == NULL)
    {
        return -1;
    }

    struct timespec tw = {.tv_sec = 0,.tv_nsec = 10000000L};

    Tuple *process_tuple;

    size_t tuple_size = sizeof(*process_tuple) + sizeof(pid_t) + sizeof(char *);
    process_tuple = calloc(argc,tuple_size);
    if (process_tuple == NULL)
    {
        return -1;
    }

//    if (pipe(pipe_array) == -1)
//    {
//        perror("pipe: ");
//        return -1;
//    }

    for (int j = 1; j < argc; j++)
    {
        child = fork();

        if (child == 0)
        {
            int
                    executed,num_of_words,num_of_chars;

            char
                    string[strlen(argv[j]) + 1],*backup = argv[j];

            snprintf(string,sizeof(string),"%s",argv[j]);

            num_of_chars = get_num_of_chars(string);

            num_of_words = get_num_of_words(string);

            char *command[num_of_chars + 1];

            preparing_the_command(num_of_words,string,command);

//            close(pipe_array[0]);
//            close(1);
//            dup2(pipe_array[1],STDOUT_FILENO);
//            write(pipe_array[1],backup,sizeof(backup));

            process_tuple[j - 1].pid = getpid();
            process_tuple[j - 1].command = backup;

            printf(" %i-PID -> %i\n %i-Command -> %s\n\n",process_tuple[j - 1].pid,process_tuple[j - 1].command);

            executed = execv(command[0],command);

            nanosleep(&tw,0);

            if (executed == -1)
            {
                exit(EXIT_FAILURE);
            }
            else
            {
                exit(EXIT_SUCCESS);
            }
        }
        else if (child == -1)
        {
            perror("fork() failed: ");
            exit(EXIT_FAILURE);
        }
    }
    printf(" PID -> %i\n Command -> %s\n\n",process_tuple[0].pid,process_tuple[0].command);
//    while ((child = waitpid(-1,&child_status,0)) != -1)
//    {
//        for (int o = 0; o < argc; o++)
//        {
//            printf(" PID -> %i\n Command -> %s\n\n",process_tuple[o].pid,process_tuple[o].command);
//        }
//        close(0);
//        close(pipe_array[1]);
//
//        dup2(pipe_array[0],STDIN_FILENO);
//        char *recipient;
//
//        read(pipe_array[0],recipient,sizeof(recipient));

//        if (!(WIFEXITED(child_status) && (WEXITSTATUS(child_status) == 0)))
//        {
//            success_or_fail = "not completed successfully";
//        }
//        else
//        {
//            success_or_fail = "completed successfully";
//        }
//        snprintf(msg_buffer,CHAR_MAX,"Command %s has %s\n",success_or_fail);
//        fputs(msg_buffer,stdout);
//    }
    fputs("All done,bye!\n",stdout);

    free(msg_buffer);

    return 0;
}

int get_num_of_chars(const char string[])
{
    int
            i = 0,num_of_chars = 0;

    while (string[i++] != '\0')
    {
        if (string[i] != ' ' && string[i] != '\t')
        {
            num_of_chars++;
        }
    }

    return num_of_chars;
}

int get_num_of_words(const char string[])
{
    int
            i = 0,num_of_words = 0;

    bool is_not_separator = false;

    while (string[i++] != '\0')
    {
        if (string[i] == ' ' || string[i] == '\t')
        {
            is_not_separator = false;
        }
        else if (!is_not_separator)
        {
            is_not_separator = true;
            num_of_words++;
        }
    }

    return num_of_words;
}

void preparing_the_command(int num_of_words,char string[],char *command[])
{
    char *token;

    for (int j = 0; j < num_of_words && (token = strtok_r(string," ",&string)); j++)
    {
        command[j] = token;
    }

    command[num_of_words] = (void *) NULL;
}

q1.h

#ifndef ASSIGNMENT2Q1_Q1_H
#define ASSIGNMENT2Q1_Q1_H
/***************
 ** LIBRARIES **
 ***************/
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>
#include <limits.h>

/*************
 ** STRUCTS **
 *************/
typedef struct
{
    pid_t pid;
    char *command;
} Tuple;

/*************************
 ** FUNCTION PROTOTYPES **
 *************************/
int get_num_of_chars(const char string[]);

int get_num_of_words(const char string[]);

void preparing_the_command(int num_of_words,char *command[]);

#endif //ASSIGNMENT2Q1_Q1_H

C：如何在 execv 之前通过管道将值从子进程传递到父进程？

如何解决C：如何在 execv 之前通过管道将值从子进程传递到父进程？

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