C中的isatty()有什么用? [英] What is isatty() in C for?

问题描述

谁能告诉我c中isatty()的参数是什么. 我有以下代码，但我不明白第一个输出的三个数字将是1，而所有其余的是0.

Hi can anyone tell me what is the paramter of isatty() in c. I have following code, but I don't understand the first output three number would be 1 and all the left is 0.

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
int main(){
        for(int i=0;i<100;i++){
                int t=isatty(i);
                printf("%d",t);
        }
        return 0;
}

推荐答案

快速浏览手册页会发现:

A quick look at your man pages would reveal:

int isatty(int fildes);

DESCRIPTION
     The isatty() function tests whether  fildes,  an  open  file
     descriptor, is associated with a terminal device.

进一步的研究将使您发现，按照惯例，文件描述符0、1和2(即STDIN_FILENO，STDOUT_FILENO和STDERR_FILENO)被设置为在程序从终端运行时指向终端.

Further investigation would lead you to the discovery that file descriptors 0, 1 and 2 (aka STDIN_FILENO, STDOUT_FILENO and STDERR_FILENO) are by convention set up to point to your terminal when your program is running from a terminal.

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