【linux c learn 之stat】擷取檔案的屬性

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NAME

       stat 擷取檔案屬性

這個函數位於<sys/stat.h>標頭檔中

函數原型：

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

參數：

path  檔案路徑+檔案名稱

buf     指向buffer的指標

返回值：

-1   遇到錯誤

0    成功返回

函數作用：

把path檔案的資訊複製到指標buf所指的結構體中。

描述

stat結構體：

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 包含裝置檔案的ID

st_ino i結點

st_mode 檔案類型和許可許可權

st_nline 檔案連結數

st_uid 使用者所有者的ID

st_gid 所屬組的ID

st_rdev 裝置ID（如果指定檔案）

st_size  所佔的位元組數

st_blksize 檔案系統I/O塊大小

st_block 分配的512B大小的

st_atime 最後訪問時間

st_mtime 最後修改時間

st_ctime 狀態最後改變時間

下面的POSIX宏定義用於核對st_mode域的檔案類型

           S_ISREG(m)  是常規檔案?           S_ISDIR(m)  目錄?           S_ISCHR(m)  字元裝置?           S_ISBLK(m)  塊裝置?           S_ISFIFO(m) FIFO?           S_ISLNK(m)  符號連結?  (Not in POSIX.1-1996.)           S_ISSOCK(m) 通訊端?  (Not in POSIX.1-1996.)

下面的標誌用於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

執行個體：

#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);}

運行結果：

[email protected]:~/linux_program/list$ ./stat stat.cFile type;                  regular fileI-node number:              679622Mode:                       100644(octal)Link count:                 1Ownership:                  UID=1000 GID=1000Preferred I/O block size:   4096 bytesFile size:                  2102 bytesBlocks allocated:           8Last status change:         Wed Jul 16 23:26:20 2014Last file access:           Wed Jul 16 23:26:35 2014Last file modification:     Wed Jul 16 23:26:20 2014

附錄為/usr/include/sys/stat.h源碼：

/*- * 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.h7.11 (Berkeley) 3/3/91 */struct stat{dev_tst_dev;/* inode's device */ino_tst_ino;/* inode's number */mode_tst_mode;/* inode protection mode */nlink_tst_nlink;/* number of hard links */uid_tst_uid;/* user ID of the file's owner */gid_tst_gid;/* group ID of the file's group */dev_tst_rdev;/* device type */off_tst_size;/* file size, in bytes */time_tst_atime;/* time of last access */longst_spare1;time_tst_mtime;/* time of last data modification */longst_spare2;time_tst_ctime;/* time of last file status change */longst_spare3;longst_blksize;/* optimal blocksize for I/O */longst_blocks;/* blocks allocated for file */u_longst_flags;/* user defined flags for file */u_longst_gen;/* file generation number */};#defineS_ISUID0004000/* set user id on execution */#defineS_ISGID0002000/* set group id on execution */#ifndef _POSIX_SOURCE#defineS_ISTXT0001000/* sticky bit */#endif#defineS_IRWXU0000700/* RWX mask for owner */#defineS_IRUSR0000400/* R for owner */#defineS_IWUSR0000200/* W for owner */#defineS_IXUSR0000100/* X for owner */#ifndef _POSIX_SOURCE#defineS_IREADS_IRUSR#defineS_IWRITES_IWUSR#defineS_IEXECS_IXUSR#endif#defineS_IRWXG0000070/* RWX mask for group */#defineS_IRGRP0000040/* R for group */#defineS_IWGRP0000020/* W for group */#defineS_IXGRP0000010/* X for group */#defineS_IRWXO0000007/* RWX mask for other */#defineS_IROTH0000004/* R for other */#defineS_IWOTH0000002/* W for other */#defineS_IXOTH0000001/* X for other */#ifndef _POSIX_SOURCE#defineS_IFMT 0170000/* type of file */#defineS_IFIFO 0010000/* named pipe (fifo) */#defineS_IFCHR 0020000/* character special */#defineS_IFDIR 0040000/* directory */#defineS_IFBLK 0060000/* block special */#defineS_IFREG 0100000/* regular */#defineS_IFLNK 0120000/* symbolic link */#defineS_IFSOCK 0140000/* socket */#defineS_ISVTX 0001000/* save swapped text even after use */#define S_BLKSIZE512/* block size used in the stat struct *//* 0666 */#defineDEFFILEMODE(S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH)#endif#defineS_ISDIR(m)((m & 0170000) == 0040000)/* directory */#defineS_ISCHR(m)((m & 0170000) == 0020000)/* char special */#defineS_ISBLK(m)((m & 0170000) == 0060000)/* block special */#defineS_ISREG(m)((m & 0170000) == 0100000)/* regular file */#defineS_ISFIFO(m)((m & 0170000) == 0010000)/* fifo */#ifndef _POSIX_SOURCE#defineS_ISLNK(m)((m & 0170000) == 0120000)/* symbolic link */#defineS_ISSOCK(m)((m & 0170000) == 0140000)/* socket */#endif#ifndef KERNEL#include <sys/cdefs.h>__BEGIN_DECLSmode_tumask __P((mode_t));intchmod __P((const char *, mode_t));intfstat __P((int, struct stat *));intmkdir __P((const char *, mode_t));intmkfifo __P((const char *, mode_t));intstat __P((const char *, struct stat *));#ifndef _POSIX_SOURCEintfchmod __P((int, mode_t));intlstat __P((const char *, struct stat *));#endif /* not POSIX */__END_DECLS#endif