man 2 stat
NAME
stat, fstat, lstat, fstatat - get file status,获取文件属性信息
SYNOPSIS
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
int stat(const char *pathname, struct stat *buf); //通过文件名 获取文件属性信息
int fstat(int fd, struct stat *buf); //通过文件描述符 获取文件属性信息
int lstat(const char *pathname, struct stat *buf); //通过链接文件 获取文件属性信息
/*
将文件pathname 的文件属性 取出 填充到 struct stat *buf
*/
int stat(const char *pathname, struct stat *buf); //通过文件名
/*
将文件 fd 的文件属性 取出 填充到 struct stat *buf
*/
int fstat(int fd, struct stat *buf); //通过文件描述符
RETURN VALUE
On success, zero is returned. On error, -1 is returned, and errno is set appropriately.
struct stat {
dev_t st_dev; /* ID of device containing file */文件所在设备的ID
ino_t st_ino; /* inode number */节点号
mode_t st_mode; /* protection */文件的类型和存取的权限
nlink_t st_nlink; /* number of hard links */链向此文件的连接数(硬连接)
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) */设备ID号,针对设备文件
off_t st_size; /* total size, in bytes */文件大小,字节为单位
blksize_t st_blksize; /* blocksize for filesystem I/O */系统块的大小
blkcnt_t st_blocks; /* number of 512B blocks allocated */文件所占块数
/* 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 */最近存取时间
struct timespec st_mtim; /* time of last modification */最近修改时间
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
};
stat命令 获取文件属性
mhr@ubuntu:~/work/linux/wenjianxitong/19$
mhr@ubuntu:~/work/linux/wenjianxitong/19$ stat test
File: 'test'
Size: 0 Blocks: 0 IO Block: 4096 regular empty file
Device: 801h/2049d Inode: 12847384 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 1000/ mhr) Gid: ( 1000/ mhr)
Access: 2020-05-03 09:01:33.072012148 -0700
Modify: 2020-05-03 09:01:29.500013664 -0700
Change: 2020-05-03 09:01:31.380012438 -0700
Birth: -
mhr@ubuntu:~/work/linux/wenjianxitong/19$
mhr@ubuntu:~/work/linux/wenjianxitong/19$
可以看出 stat 命令使用 stat()函数封装出来的,ls 各种参数的 都是从stat 中获取信息。
实验1, 通过 stat 获取文件大小信息
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
/*
注意,st_size的类型是 off_t , 不是int
off_t类型具体是多少位是不清楚的,只是在一些体系中,会把 off_t 定义成32位的,
*/
static off_t flen(const char *fname)
{
struct stat statres;
if(stat(fname,&statres) < 0)
{
perror("stat()");
exit(1);
}
return statres.st_size;
}
int main(int argc, char *argv[])
{
if(argc < 2)
{
fprintf(stderr,"Usage......\n");
exit(1);
}
printf("%lld\n",(long long)flen(argv[1]));
exit(0);
}
mhr@ubuntu:~/work/linux/wenjianxitong/19$ gcc fslen.c
mhr@ubuntu:~/work/linux/wenjianxitong/19$ ./a.out test
0
mhr@ubuntu:~/work/linux/wenjianxitong/19$
mhr@ubuntu:~/work/linux/wenjianxitong/19$ stat test
File: 'test'
Size: 0 Blocks: 0 IO Block: 4096 regular empty file
Device: 801h/2049d Inode: 12847384 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 1000/ mhr) Gid: ( 1000/ mhr)
Access: 2020-05-03 09:01:33.072012148 -0700
Modify: 2020-05-03 09:01:29.500013664 -0700
Change: 2020-05-03 09:01:31.380012438 -0700
Birth: -
mhr@ubuntu:~/work/linux/wenjianxitong/19$