【APUE】文件属性

函数原型

NAME
       stat, fstat, lstat, fstatat - get file status

SYNOPSIS
       #include 
       #include 
       #include 

       int stat(const char *pathname, struct stat *statbuf);
       int fstat(int fd, struct stat *statbuf);
       int lstat(const char *pathname, struct stat *statbuf);

       #include            /* Definition of AT_* constants */
       #include 

       int fstatat(int dirfd, const char *pathname, struct stat *statbuf,
                   int flags);

	struct stat {
	   dev_t     st_dev;         /* ID of device containing file */
	   ino_t     st_ino;         /* Inode number */
	   mode_t    st_mode;        /* File type and mode */
	   nlink_t   st_nlink;       /* Number of hard links */
	   uid_t     st_uid;         /* User ID of owner */
	   gid_t     st_gid;         /* Group ID of owner */
	   dev_t     st_rdev;        /* Device ID (if special file) */
	   off_t     st_size;        /* Total size, in bytes */
	   blksize_t st_blksize;     /* Block size for filesystem I/O */
	   blkcnt_t  st_blocks;      /* Number of 512B blocks allocated */

	   /* Since Linux 2.6, the kernel supports nanosecond
		  precision for the following timestamp fields.
		  For the details before Linux 2.6, see NOTES. */

	   struct timespec st_atim;  /* Time of last access */
	   struct timespec st_mtim;  /* Time of last modification */
	   struct timespec st_ctim;  /* Time of last status change */

	#define st_atime st_atim.tv_sec      /* Backward compatibility */
	#define st_mtime st_mtim.tv_sec
	#define st_ctime st_ctim.tv_sec
	};

Demo

khead.h

#include 
#include 
#include 
#include 

extern int errno;

void err_msg(const char* str) {
        printf("%s\n", str);
        printf("errno: %d\terrmsg: %s\n", errno, strerror(errno));
}

stat.h

#include "khead.h"
#include 
#include 

int main(int argc, char* argv[]) {
        if (argc != 2) {
                err_msg("please input a filename");
        }
        int ret;
        struct stat st;
        ret = stat(argv[1], &st); // 如果是链接文件，会跳到最终的文件查看属性
        if (ret != 0) {
                err_msg("stat err");
        }
        printf("size is:%ld\n", st.st_size);
        return 0;
}

lstat.h

#include "khead.h"
#include 
#include 

int main(int argc, char* argv[]) {
        if (argc != 2) {
                err_msg("please input a filename");
        }
        int ret;
        struct stat st;
        ret = lstat(argv[1], &st); // 可以查看链接文件的属性，不会跳到最终的文件
        if (ret != 0) {
                err_msg("stat err");
        }
        printf("size is:%ld\n", st.st_size);
        return 0;
}