檢測文件類型（常規文件，目錄，符號鏈接等）

Question

我試圖使用stat(2)來確定argv [i]是否是常規文件，目錄或符號鏈接。有兩件事情，我不從stat(2) man頁面瞭解：

1. 那是什麼stat(2)需要（即BUF ARG）

   int stat(const char *path, struct stat *buf); 
   

2. 如何使用第二個參數返回值以確定它是否是reg文件，dir或sym鏈接？

Answer 1

要回答第一個問題，你可以取消引用stat結構的實例和傳遞取消引用值stat()來填充實例的字段值：

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

/* ... */ 

struct stat foo; 
const char *path = "https://stackoverflow.com/a/b/c"; 

/* test the result of stat() to make sure it ran correctly */ 

if (stat(path, &foo) != 0) { 
    fprintf(stderr, "something went wrong with stat()\n"); 
    exit(EXIT_FAILURE); 
} 

/* now do stuff with foo; e.g. from docs: */ 

switch (foo.st_mode & S_IFMT) { 
    case S_IFBLK: printf("block device\n");   break; 
    case S_IFCHR: printf("character device\n");  break; 
    case S_IFDIR: printf("directory\n");    break; 
    case S_IFIFO: printf("FIFO/pipe\n");    break; 
    case S_IFLNK: printf("symlink\n");     break; 
    case S_IFREG: printf("regular file\n");   break; 
    case S_IFSOCK: printf("socket\n");     break; 
    default:  printf("unknown?\n");    break; 
} 

要回答第二個問題，從您鏈接到文件：

The following POSIX macros are defined to check 
the file type using the st_mode field: 

S_ISREG(m) - is it a regular file? 
S_ISDIR(m) - directory? 
S_ISCHR(m) - character device? 
S_ISBLK(m) - block device? 
S_ISFIFO(m) - FIFO (named pipe)? 
S_ISLNK(m) - symbolic link? (Not in POSIX.1-1996.) 
S_ISSOCK(m) - socket? (Not in POSIX.1-1996.) 

的st_mode場被填充，如果stat()是成功的，那麼你可以通過這個結果上面列出的宏：

if (S_ISREG(foo.st_mode)) { 
    fprintf(stderr, "whatever foo points to is a regular file\n"); 
} 
else { 
    fprintf(stderr, "whatever foo points to is something else\n"); 
} 

你應該首先測試的stat()結果，以確保您在st_mode等領域都有可用值。再次參考文檔，該文檔實際上寫得很好，或者查看上面的代碼片段。