打开一个cmd程序的全部功能（I / O） [英] Open a cmd program with full functionality (i/o)

问题描述

我试过的popen（）和它运作良好的输出R作为第二个参数传递;我知道你可以使用W写作模式，它为我工作（该方案是只有一个 scanf（）的）。我的问题是如何使用append（一）模式。你既可以写和读，你怎么知道什么时候该程序输出的东西，当它要求用户输入？

I tried popen() and it is working well for output with "r" passed as a second argument; I know you can use "w" as writing mode and it worked for me (the program was just one scanf()). My question is how to use the append ("a") mode. You can both write and read, how do you know when the program is outputting something and when it's requesting for user input?

推荐答案

的popen使用的管道（这是P中的popen）和管道是单向的。可以读取或从管的一端，而不是两个写。两者都要读/写访问，你应该使用socketpair来代替。我用这个在我的计划时，我想是这样的popen，但读/写：

popen uses a pipe (that's the "p" in "popen") and pipes are unidirectional. You can either read or write from one end of a pipe, not both. To get both read/write access you should use a socketpair instead. I use this in my programs when I want something like popen, but for read/write:

    #include <sys/types.h>
    #include <sys/socket.h>
    #include <stdio.h>
    #include <unistd.h>

    FILE *sopen(const char *program)
    {
        int fds[2];
        pid_t pid;

        if (socketpair(AF_UNIX, SOCK_STREAM, 0, fds) < 0)
            return NULL;

        switch(pid=vfork()) {
        case -1:    /* Error */
            close(fds[0]);
            close(fds[1]);
            return NULL;
        case 0:     /* child */
            close(fds[0]);
            dup2(fds[1], 0);
            dup2(fds[1], 1);
            close(fds[1]);
            execl("/bin/sh", "sh", "-c", program, NULL);
            _exit(127);
        }
        /* parent */
        close(fds[1]);
        return fdopen(fds[0], "r+");
    }

请注意，由于它不返回孩子的PID，你有小孩程序退出后，一个僵尸进程。 （除非你设置SIGCHLD ...）

Note that since it doesn't return the child's pid, you'll have a a zombie process after the child program exits. (Unless you set up SIGCHLD...)

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