打印文件权限类似于C使用状态（2）'ls -l命令“ [英] Printing file permissions like 'ls -l' using stat(2) in C

问题描述

我试图写模拟UNIX命令一个小的C程序
    的ls -l <​​/ code>。要做到这一点，我现在用的 STAT（2）系统调用，并跑进一个小嗝写权限。我有保存文件的权限从 ST_MODE A mode_t 变量，它会不会很难解析该值到s字符串重新presentation，但我只是想知道如果有需要做比这更好的办法。

I am trying to write a small C program that emulates the unix command ls -l. To do so, I am using the stat(2) syscall and have ran into a small hiccup writing the permissions. I have a mode_t variable which holds the file permissions from st_mode, and it wouldn't be hard to parse that value into s string representation, but I was just wondering if there is a better way to be doing it than that.

推荐答案

例如，从谷歌

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

int main(int argc, char **argv)
{
    if(argc != 2)    
        return 1;

    struct stat fileStat;
    if(stat(argv[1],&fileStat) < 0)    
        return 1;

    printf("Information for %s\n",argv[1]);
    printf("---------------------------\n");
    printf("File Size: \t\t%d bytes\n",fileStat.st_size);
    printf("Number of Links: \t%d\n",fileStat.st_nlink);
    printf("File inode: \t\t%d\n",fileStat.st_ino);

    printf("File Permissions: \t");
    printf( (S_ISDIR(fileStat.st_mode)) ? "d" : "-");
    printf( (fileStat.st_mode & S_IRUSR) ? "r" : "-");
    printf( (fileStat.st_mode & S_IWUSR) ? "w" : "-");
    printf( (fileStat.st_mode & S_IXUSR) ? "x" : "-");
    printf( (fileStat.st_mode & S_IRGRP) ? "r" : "-");
    printf( (fileStat.st_mode & S_IWGRP) ? "w" : "-");
    printf( (fileStat.st_mode & S_IXGRP) ? "x" : "-");
    printf( (fileStat.st_mode & S_IROTH) ? "r" : "-");
    printf( (fileStat.st_mode & S_IWOTH) ? "w" : "-");
    printf( (fileStat.st_mode & S_IXOTH) ? "x" : "-");
    printf("\n\n");

    printf("The file %s a symbolic link\n", (S_ISLNK(fileStat.st_mode)) ? "is" : "is not");

    return 0;
}

结果：

Information for 2.c
---------------------------
File Size:              1223 bytes
Number of Links:        1
File inode:             39977236
File Permissions:       -rw-r--r--

The file is not a symbolic link

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