【linux c learn 之stat】获取文件的属性
NAME
dev_t 包括设备文件的ID
以下的标志用于st_mode域：
实例：
执行结果：
stat 获取文件属性
这个函数位于<sys/stat.h>头文件里
函数原型：
int stat(const char *path, struct stat *buf);
參数：
path 文件路径+文件名称
buf 指向buffer的指针
返回值：
-1 遇到错误
0 成功返回
函数作用：
把path文件的信息拷贝到指针buf所指的结构体中。
描写叙述
stat结构体：
struct stat {
dev_t st_dev; /* ID of device containing file */
ino_t st_ino; /* inode number */
mode_t st_mode; /* protection */
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; /* blocksize for filesystem I/O */
blkcnt_t st_blocks; /* number of 512B blocks allocated */
time_t st_atime; /* time of last access */
time_t st_mtime; /* time of last modification */
time_t st_ctime; /* time of last status change */
};dev_t 包括设备文件的ID
st_ino i结点
st_mode 文件类型和许可权限
st_nline 文件链接数
st_uid 用户全部者的ID
st_gid 所属组的ID
st_rdev 设备ID（假设指定文件）
st_size 所占的字节数
st_blksize 文件系统I/O块大小
st_block 分配的512B大小的
st_atime 最后訪问时间
st_mtime 最后改动时间
st_ctime 状态最后改变时间
以下的POSIX宏定义用于核对st_mode域的文件类型
S_ISREG(m) 是常规文件?
S_ISDIR(m) 文件夹?
S_ISCHR(m) 字符设备?
S_ISBLK(m) 块设备?
S_ISFIFO(m) FIFO?
S_ISLNK(m) 符号链接? (Not in POSIX.1-1996.)
S_ISSOCK(m) 套接字? (Not in POSIX.1-1996.)以下的标志用于st_mode域：
S_IFMT 0170000 bit mask for the file type bit fields
S_IFSOCK 0140000 socket
S_IFLNK 0120000 symbolic link
S_IFREG 0100000 regular file
S_IFBLK 0060000 block device
S_IFDIR 0040000 directory
S_IFCHR 0020000 character device
S_IFIFO 0010000 FIFO
S_ISUID 0004000 set-user-ID bit
S_ISGID 0002000 set-group-ID bit (see below)
S_ISVTX 0001000 sticky bit (see below)
S_IRWXU 00700 mask for file owner permissions
S_IRUSR 00400 owner has read permission
S_IWUSR 00200 owner has write permission
S_IXUSR 00100 owner has execute permission
S_IRWXG 00070 mask for group permissions
S_IRGRP 00040 group has read permission
S_IWGRP 00020 group has write permission
S_IXGRP 00010 group has execute permission
S_IRWXO 00007 mask for permissions for others (not in group)
S_IROTH 00004 others have read permission
S_IWOTH 00002 others have write permission
S_IXOTH 00001 others have execute permission实例：
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <time.h>
#include <stdlib.h>
int main(int argc, char *argv[])
{
struct stat info;
if (argc != 2)
{
fprintf(stderr, "Usage: %s <pathname>\n", argv[0]);
exit(EXIT_FAILURE);
}
if (stat(argv[1], &info) == -1)
{
perror("stat");
exit(EXIT_FAILURE);
}
printf("File type; ");
switch(info.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;
}
printf("I-node number: %ld\n", (long)info.st_ino);
printf("Mode: %lo(octal)\n",
(unsigned long)info.st_mode);
printf("Link count: %ld\n", (long)info.st_nlink);
printf("Ownership: UID=%ld GID=%ld\n",
(long)info.st_uid, (long)info.st_gid);
printf("Preferred I/O block size: %ld bytes\n",
(long) info.st_blksize);
printf("File size: %lld bytes\n",
(long long) info.st_size);
printf("Blocks allocated: %lld\n",
(long long) info.st_blocks);
printf("Last status change: %s", ctime(&info.st_ctime));
printf("Last file access: %s", ctime(&info.st_atime));
printf("Last file modification: %s", ctime(&info.st_mtime));
exit(EXIT_SUCCESS);
}执行结果：
liujl@liujl-ThinkPad-Edge-E431:~/linux_program/list$ ./stat stat.c File type; regular file I-node number: 679622 Mode: 100644(octal) Link count: 1 Ownership: UID=1000 GID=1000 Preferred I/O block size: 4096 bytes File size: 2102 bytes Blocks allocated: 8 Last status change: Wed Jul 16 23:26:20 2014 Last file access: Wed Jul 16 23:26:35 2014 Last file modification: Wed Jul 16 23:26:20 2014
附录为/usr/include/sys/stat.h源代码：
/*-
* Copyright (c) 1982, 1986, 1989 The Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)stat.h 7.11 (Berkeley) 3/3/91
*/
struct stat
{
dev_t st_dev; /* inode's device */
ino_t st_ino; /* inode's number */
mode_t st_mode; /* inode protection mode */
nlink_t st_nlink; /* number of hard links */
uid_t st_uid; /* user ID of the file's owner */
gid_t st_gid; /* group ID of the file's group */
dev_t st_rdev; /* device type */
off_t st_size; /* file size, in bytes */
time_t st_atime; /* time of last access */
long st_spare1;
time_t st_mtime; /* time of last data modification */
long st_spare2;
time_t st_ctime; /* time of last file status change */
long st_spare3;
long st_blksize; /* optimal blocksize for I/O */
long st_blocks; /* blocks allocated for file */
u_long st_flags; /* user defined flags for file */
u_long st_gen; /* file generation number */
};
#define S_ISUID 0004000 /* set user id on execution */
#define S_ISGID 0002000 /* set group id on execution */
#ifndef _POSIX_SOURCE
#define S_ISTXT 0001000 /* sticky bit */
#endif
#define S_IRWXU 0000700 /* RWX mask for owner */
#define S_IRUSR 0000400 /* R for owner */
#define S_IWUSR 0000200 /* W for owner */
#define S_IXUSR 0000100 /* X for owner */
#ifndef _POSIX_SOURCE
#define S_IREAD S_IRUSR
#define S_IWRITE S_IWUSR
#define S_IEXEC S_IXUSR
#endif
#define S_IRWXG 0000070 /* RWX mask for group */
#define S_IRGRP 0000040 /* R for group */
#define S_IWGRP 0000020 /* W for group */
#define S_IXGRP 0000010 /* X for group */
#define S_IRWXO 0000007 /* RWX mask for other */
#define S_IROTH 0000004 /* R for other */
#define S_IWOTH 0000002 /* W for other */
#define S_IXOTH 0000001 /* X for other */
#ifndef _POSIX_SOURCE
#define S_IFMT 0170000 /* type of file */
#define S_IFIFO 0010000 /* named pipe (fifo) */
#define S_IFCHR 0020000 /* character special */
#define S_IFDIR 0040000 /* directory */
#define S_IFBLK 0060000 /* block special */
#define S_IFREG 0100000 /* regular */
#define S_IFLNK 0120000 /* symbolic link */
#define S_IFSOCK 0140000 /* socket */
#define S_ISVTX 0001000 /* save swapped text even after use */
#define S_BLKSIZE 512 /* block size used in the stat struct */
/* 0666 */
#define DEFFILEMODE (S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH)
#endif
#define S_ISDIR(m) ((m & 0170000) == 0040000) /* directory */
#define S_ISCHR(m) ((m & 0170000) == 0020000) /* char special */
#define S_ISBLK(m) ((m & 0170000) == 0060000) /* block special */
#define S_ISREG(m) ((m & 0170000) == 0100000) /* regular file */
#define S_ISFIFO(m) ((m & 0170000) == 0010000) /* fifo */
#ifndef _POSIX_SOURCE
#define S_ISLNK(m) ((m & 0170000) == 0120000) /* symbolic link */
#define S_ISSOCK(m) ((m & 0170000) == 0140000) /* socket */
#endif
#ifndef KERNEL
#include <sys/cdefs.h>
__BEGIN_DECLS
mode_t umask __P((mode_t));
int chmod __P((const char *, mode_t));
int fstat __P((int, struct stat *));
int mkdir __P((const char *, mode_t));
int mkfifo __P((const char *, mode_t));
int stat __P((const char *, struct stat *));
#ifndef _POSIX_SOURCE
int fchmod __P((int, mode_t));
int lstat __P((const char *, struct stat *));
#endif /* not POSIX */
__END_DECLS
#endif
