在输入，输出和重定向中使用execvp [英] Using execvp with Input,Output and redirection

问题描述

在C程序中，假设我要使用Exec函数来执行给定程序，例如，如果我只想尝试ls -l我将做类似的事情

In a C program, let's say i wann use Exec functions for executing a given program, for example if i wanna just try ls -l i'll do something like

args[0]="ls";
args[1]="-l";
args[2]=NULL;

...
execvp("ls", args); 

一切都很好.现在，如果我还想将重定向添加到文件(或stderr)，该怎么办? 我被困住了，很明显，将> log.txt作为数组的第3个条目添加是行不通的，但是我不知道如何进行.

and it's all fine. Now what if i wanna also add the redirection to a file (or to stderr)? I'm stuck, it's obvious that adding >log.txt as a 3rd entry in the array won't work, but I don't know how to proceed.

而且，如果我想传递一些输入参数怎么办?如果我想执行GCC命令，例如"gcc -o in redirection> log.txt"，该怎么办?

And also, what if I wanna pass some Input parameters? What if i wanna execute a GCC command like "gcc -o out in redirection>log.txt" ?

[评论更新:]

这是一个C程序，它模拟可以运行字符串"，包含命令，参数列表，输入和重定向的字符串的shell.

It's a C program that simulate a shell which can "run strings", string that contains a command, a list o parameters, input and a redirection.

推荐答案

只需设置文件描述符，因为exec -d进程将找到它们，然后执行.
为此，您需要open，dup2和close.

Just set up your file descriptors as the exec-d process shall find them and then do the exec.
For that you need open, dup2 and close.

exec系列中的所有功能只是用您说的任何内容替换当前进程.

All functions in the exec-family just replace the current process with whatever one you say.

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