使用fork，execvp然后重新输出到套接字的两个命令的管道

Question

我有两个命令cmd1和cmd2，我必须在子节点中执行cmd1，将输出重定向到另一个子节点，然后使用cmd1的输出执行cmd2作为论据。然后，我必须将输出重定向到与套接字连接的远程客户端（telnet）。我无法弄清楚问题，但我的解决方案不会将cmd1输出重定向到cmd2。

if(fork() == 0) 
    { 
     //Process to compute cmd1 
     char *arg[2]; 
     arg[0] = cmd1; 
     arg[1] = NULL; 
     dup(piped[1]); 
     close(piped[0]); 
     close(piped[1]); 
     execvp(cmd1,arg); 

    } 
    if(fork() == 0) 
    { 
     //Process to compute cmd2 
     dup2(newsockfd,STDOUT_FILENO); 
     dup2(newsockfd,STDERR_FILENO); 
     char *arg[2]; 
     arg[0] = cmd2; 
     arg[1] = NULL; 
     dup(piped[0]); 
     close(piped[0]); 
     close(piped[1]); 
     execvp(cmd2,arg); 
    } 

只是要清楚。这个问题是不是在插座inizilization或管道，这就是为什么我只报告主要部分

Answer 1

根据我的了解，你想要什么会像下面

if(fork() == 0) 
{ 
    //Process to compute cmd1 
    char *arg[2]; 
    arg[0] = cmd1; 
    arg[1] = NULL; 
    dup2(piped[1],STDOUT_FILENO); //Redirect stdout to pipe's write end 
    dup2(piped[1],STDERR_FILENO); //Redirect stderr to pipe's write end 
    close(piped[0]); 
    close(piped[1]); 
    close(newsockfd); 
    execvp(cmd1,arg); 
} 

if(fork() == 0) 
{ 
    //Process to compute cmd2 
    char *arg[2]; 
    arg[0] = cmd2; 
    arg[1] = NULL; 
    dup2(piped[0],STDIN_FILENO); //Redirect pipe's read end to stdin 
    dup2(newsockfd,STDOUT_FILENO); //Redirect stdout to socket 
    dup2(newsockfd,STDERR_FILENO); //Redirect stderr to socket 
    close(piped[0]); 
    close(piped[1]); 
    close(newsockfd); 
    execvp(cmd2,arg); 
} 

close(piped[0]); 
close(piped[1]); 
close(newsockfd);