C:如何将stderr从系统命令重定向到stdout或文件? [英] C: how to redirect stderr from System-command to stdout or file?

问题描述

shell命令$ avrdude -c usbtiny将文本输出到stderr.我无法用诸如无头多cos之类的命令来阅读它，它不是标准输出.我希望文本输出到文件或文件.我该如何在C语言中完成?我已经尝试通过我的最后一个问题解决问题，但仍未解决.

The shell command $ avrdude -c usbtiny outputs text to stderr. I cannot read it with commmands such as head-less-more cos it is not stdout. I want the text to stdout or to a file. How can I do it in C? I have tried to solve the problem by my last question but still unsolved.

推荐答案

我没有在OpenBSD中尝试过类似的方法，但是在至少一些* nix类系统中，可以使用dup2来实现. /p>

I've not tried something like this in OpenBSD, but in at least a few *nix-like systems, you can do this using dup2.

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

int main(void) {  

  fprintf(stderr, "This goes to stderr\n");

  dup2(1, 2);  //redirects stderr to stdout below this line.

  fprintf(stderr, "This goes to stdout\n");
}

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