我想写一个程序，最终将复制它的功能

program1 |程序| programX

所以我想将programX的输出重定向到programX 1的输入 .

For the sake of simplicity, I would like to start off with only two programs and a single pipe.

在伪代码中，我的方法看起来像这样：

1. create a pipe for communication between child1 and child2
2. fork parent to create child1 and fork parent again to create child2
3. close unneeded pipe ends in children
4. redirect the output of execvp() from child 1 into the write-end of the pipe via dup2, so that child2 receives whatever that program puts out
5. child2 reads the pipe and receives output from program of child1
6. execute execvp() with the received data

到目前为止一直很好，这是我现在拥有的：

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

#define READ  0
#define WRITE 1

int main(int argc, const char * argv[])
{

    //create a unidirectional pipe
    int aPipe[2];

    if(pipe(aPipe)){

        perror("pipe call");
        exit(EXIT_FAILURE);

    }

    //create child 1 ("sender")
    pid_t child_pid = fork();

    if(child_pid < (pid_t)0)
    {
        perror("fork call failed");
        exit(EXIT_FAILURE);
    }
    else if(child_pid == (pid_t) 0){

        //in child1
        close(aPipe[READ]);

        //get actual arguments from argv array
        const char **realArgs = malloc(sizeof(char *) * (argc-1));

        for(int i=1;i<argc;i++){

            realArgs[i-1] = argv[i];

        }

        //redirect standard output into write-end of the pipe
        dup2(aPipe[WRITE], STDOUT_FILENO);
        close(aPipe[WRITE]);
        execvp(argv[0], realArgs);

        //exec call failed
        exit(EXIT_FAILURE);



    }


    //parent
    //create second child ("receiver")
    pid_t child2_pid = fork();

    if(child2_pid == (pid_t)0){

        //close unneeded pipe end
        close(aPipe[WRITE]);

        char buffer[1024];
        char **argv2 = malloc(sizeof(char *));

        while (read(aPipe[READ], buffer, sizeof(buffer)) != 0)
        {

            argv2[0] = buffer;
            printf("buffer = %s", buffer);
            //execvp("sort", argv2);

        }

        close(aPipe[READ]);
        exit(EXIT_SUCCESS);

    }

    //close unneeded pipe ends, parent does not need the pipe
    close(aPipe[WRITE]);
    close(aPipe[READ]);

    exit(EXIT_SUCCESS);

    return 0;
}

这几乎实现了我想要做的事情，但是child2中的输出似乎再次写入管道，导致写入自己的管道 . 我想，我在这里可能完全错了，尽管通过printf关闭了child2中的写端，但是它写入了自己的管道（当我将STDOUT重定向到管道的写端时）并再次读取它 . 所以输出看起来像这样

当我使用参数 who 和 sort 运行程序时

myProg谁排序

我得到以下输出：

buffer = buffer = martine ****** console 4月24日12:59

编辑：

如何在execvp中设置sort命令的输入（“sort”，argsArr）; ？ sort通常采用文件名，所以我该如何处理呢？

c fork pipe dup2