如何捕获execvp的输出 [英] How to capture output of execvp

问题描述

我正在开发一个程序，该程序使用execvp执行程序.它需要捕获子过程的结果并在主过程中对其进行解析.似乎有一种方法可以使用命名管道和duping.我正在尝试寻找一个很好的例子，但是到目前为止还没有运气.如果有人对此有任何指示，链接和/或建议，我将不胜感激.

I'm developing a program which executes a program using execvp. It needs to capture the results of the child process and parse them in the main process. It seems there is a way, using named pipes, and duping. I'm trying to hunt down a good example of this, but so far no luck. If anyone has any pointers, links and/or suggestions about this, I'd greatly appreciate it.

推荐答案

您不需要命名管道；未命名的管道可以正常工作.实际上，通常您可以只使用popen而不是自己执行pipe/fork/dup/exec. popen的工作方式如下(尽管您的libc的实现可能会进行更多的错误检查):

You don't need named pipes; unnamed pipes work just fine. Actually, often you can just use popen instead of doing the pipe/fork/dup/exec yourself. popen works like this (though your libc's implementation likely has more error checking):

FILE *popen(const char *command, const char *type) {
    int fds[2];
    const char *argv[4] = {"/bin/sh", "-c", command};
    pipe(fds);
    if (fork() == 0) {
        close(fds[0]);
        dup2(type[0] == 'r' ? 0 : 1, fds[1]);
        close(fds[1]);
        execvp(argv[0], argv);
        exit(-1);
    }
    close(fds[1]);
    return fdopen(fds[0], type);
}

这将创建一个未命名的管道和fork s.在子级中，它将stdout(或stdin)重新连接到管道的一端，然后exec子级.父级可以简单地从管道的另一端读取(或写入).

This creates an unnamed pipe, and forks. In the child, it reattaches stdout (or stdin) to one end of the pipe, then execs the child. The parent can simply read (or write) from the other end of the pipe.

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