C使用exec和pipe创建多个子进程

Question

我想创建与用户在参数中发送的子进程一样多的子进程。我成功了。但是，我必须使用exec函数创建子进程，我不知道如何做到这一点执行官。此外，我希望每个子进程都能使用pipe与主进程（父进程）进行通信。我不知道怎么做。到目前为止，我设法写了这样的东西：

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

   int main(int argc, char **argv)
   {
        pid_t pid;
        if(argc < 3)
        {
                printf("Not enought arguments");
                exit(0);
        }
        int number = atoi(argv[2]); // number of childern
        pid_t pids[number],pid_s;
        int i,n=number,status;
        int pipes[number*2];
        char buff[512];
        if(strcmp("-p", argv[1]) == 0)
        {
                //
        }
        if(strcmp("-f", argv[1]) == 0)
        {
                //
        }

        switch (pid = fork()) {
           case -1:
                        perror("Error in fork");
                        exit(0);
                        break;
           case 0:
                   for(i=0; i < n; i++)
                   {
                           if((pids[i] = fork()) < 0)
                           {
                                   perror("error fork");
                           }
                           else if(pids[i] == 0)
                           {
                                close(pipes[0]);
                                char *reply = "message";
                                write(pipes[1], reply, strlen(reply)+1);
                                execvp(argv[0],NULL);
                           }
                   }
                   while(n > 0)
                   {
                           pid_s = wait(&status);
                           --n;
                   }
                          break;
            default:
               close(pipes[1]);
               read(pipes[0],buff,80);
               printf("Message: %s", buff);
                   if(wait(0) == -1)
                   {
                   }
                          break;
         }
        return 0;
}

我更正了代码，孩子通过exec创建了一个新的进程。我想通过管道与孩子沟通主要过程。循环做得最好？

Answer 1

此示例代码，截取自：http://www.cs.ecu.edu/karl/4630/sum01/example1.html显示了如何使用execvp()功能，我做了一些小修改。

它使用函数parsecmd（cmd，argv），这里不写它，但它在空格处中断cmd，并将片段存储到（本地数组）argv[]中，后面跟着一个空指针。例如，parsecmd（"吃香蕉"，argv）将按如下方式设置argv。

   argv[0] = "eat"
   argv[1] = "the"
   argv[2] = "banana"
   argv[3] = NULL
This example also presumes that there might be other child processes running in background, and that they might terminate while the shell is waiting for the current command to stop. A function called process_terminated is use to handle the termination of a background process. It is not written here.
int runcmd(char *cmd)
{
  char* argv[MAX_ARGS];
  pid_t child_pid;
  int child_status;
  parsecmd(cmd,argv);
  child_pid = fork();
  if(child_pid == 0) {
    /* This is done by the child process. */
    execvp(argv[0], argv);
    /* If execvp returns, it must have failed. */
    fprintf( stderr, "execvp failed due to %sn", strerror(errno) );
    exit(0);
  }
  else {
     /* This is run by the parent.  Wait for the child
        to terminate. */
     do {
       pid_t tpid = wait(&child_status);
       if(tpid != child_pid) process_terminated(tpid);
     } while(tpid != child_pid);
     return child_status;
  }
}