man 3 stat函数翻译

NAME
       stat, fstat, lstat - get file status


SYNOPSIS
       #include <sys/types.h>
       #include <sys/stat.h>
       #include <unistd.h>


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


   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):


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


   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):


       lstat():
           _BSD_SOURCE || _XOPEN_SOURCE >= 500 ||
           _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
           || /* Since glibc 2.10: */ _POSIX_C_SOURCE >= 200112L


DESCRIPTION
       These functions return information about a file.  No permissions are required  on
       the file itself, but—in the case of stat() and lstat() — execute (search) permis‐
       sion is required on all of the directories in path that lead to the file.


       stat() stats the file pointed to by path and fills in buf.


       lstat() is identical to stat(), except that if path is a symbolic link, then  the
       link itself is stat-ed, not the file that it refers to.


       fstat()  is  identical to stat(), except that the file to be stat-ed is specified
       by the file descriptor fd.


       sion is required on all of the directories in path that lead to the file.


       stat() stats the file pointed to by path and fills in buf.


       lstat() is identical to stat(), except that if path is a symbolic link, then  the
       These functions return information about a file.  No permissions are required  on
       the file itself, but—in the case of stat() and lstat() — execute (search) permis‐
       sion is required on all of the directories in path that lead to the file.
           || /* Since glibc 2.10: */ _POSIX_C_SOURCE >= 200112L


DESCRIPTION
       These functions return information about a file.  No permissions are required  on
       the file itself, but—in the case of stat() and lstat() — execute (search) permis‐
       sion is required on all of the directories in path that lead to the file.


       stat() stats the file pointed to by path and fills in buf.


       lstat() is identical to stat(), except that if path is a symbolic link, then  the
       link itself is stat-ed, not the file that it refers to.


       fstat()  is  identical to stat(), except that the file to be stat-ed is specified
       by the file descriptor fd.


       All of these system calls return a stat structure, which contains  the  following
       fields:


           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 file system 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 */
           };


       The  st_dev field describes the device on which this file resides.  (The major(3)
       and minor(3) macros may be useful to decompose the device ID in this field.)


       The st_rdev field describes the device that this file (inode) represents.


       The st_size field gives the size of the file (if it is a regular file or  a  sym‐
       bolic  link) in bytes.  The size of a symbolic link is the length of the pathname
       it contains, without a terminating null byte.


       The st_blocks field indicates  the  number  of  blocks  allocated  to  the  file,
       512-byte units.  (This may be smaller than st_size/512 when the file has holes.)


       The  st_blksize  field  gives the "preferred" blocksize for efficient file system
       I/O.  (Writing to a file in smaller chunks may cause an inefficient  read-modify-
       rewrite.)


       Not  all  of  the Linux file systems implement all of the time fields.  Some file
       system types allow mounting in such a way that file and/or directory accesses  do
       not  cause  an update of the st_atime field.  (See noatime, nodiratime, and rela‐
       time in mount(8), and related information in mount(2).)  In addition, st_atime is
       not updated if a file is opened with the O_NOATIME; see open(2).


       The  field  st_atime  is  changed  by  file  accesses, for example, by execve(2),
       mknod(2), pipe(2), utime(2) and read(2) (of more than zero  bytes).   Other  rou‐
       tines, like mmap(2), may or may not update st_atime.


       The  field  st_mtime  is changed by file modifications, for example, by mknod(2),
       truncate(2), utime(2) and write(2) (of more than zero bytes).  Moreover, st_mtime
       of a directory is changed by the creation or deletion of files in that directory.
       The st_mtime field is not changed for changes in owner, group, hard  link  count,
       or mode.


       The  field  st_ctime is changed by writing or by setting inode information (i.e.,
       owner, group, link count, mode, etc.).


       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.)


       The following flags are defined for the st_mode field:


           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
       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.)


       The following flags are defined for the st_mode field:


           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


       The  set-group-ID  bit  (S_ISGID)  has  several special uses.  For a directory it
       indicates that BSD semantics is to be used  for  that  directory:  files  created
       there  inherit their group ID from the directory, not from the effective group ID
       of the creating process, and directories created there will also get the  S_ISGID
       bit  set.   For  a file that does not have the group execution bit (S_IXGRP) set,
       the set-group-ID bit indicates mandatory file/record locking.


       The sticky bit (S_ISVTX) on a directory means that a file in that  directory  can
       be  renamed  or deleted only by the owner of the file, by the owner of the direc‐
       tory, and by a privileged process.


RETURN VALUE
       On success, zero is returned.  On error, -1 is returned, and errno is set  appro‐
       priately.


ERRORS
       EACCES Search  permission is denied for one of the directories in the path prefix
              of path.  (See also path_resolution(7).)


       EBADF  fd is bad.


       EFAULT Bad address.


       ELOOP  Too many symbolic links encountered while traversing the path.


       ENAMETOOLONG
              path is too long.


       ENOENT A component of path does not exist, or path is an empty string.


       ENOMEM Out of memory (i.e., kernel memory).


       ENOTDIR
              A component of the path prefix of path is not a directory.


       EOVERFLOW
              path or fd refers to a file whose size, inode number, or number of  blocks
              cannot  be  represented  in,  respectively,  the  types  off_t,  ino_t, or
              blkcnt_t.  This error can occur when, for example, an application compiled
              on a 32-bit platform without -D_FILE_OFFSET_BITS=64 calls stat() on a file
              whose size exceeds (1<<31)-1 bytes.


CONFORMING TO
       These system calls conform to SVr4, 4.3BSD, POSIX.1-2001.


       According to POSIX.1-2001, lstat() on a symbolic link need return valid  informa‐
       tion  only  in the st_size field and the file-type component of the st_mode field
       of the stat structure.  POSIX.-2008 tightens the specification, requiring lstat()
       to return valid information in all fields except the permission bits in st_mode.


       Use  of  the  st_blocks  and  st_blksize fields may be less portable.  (They were
       introduced in BSD.  The interpretation differs between systems, and possibly on a
       single  system  when NFS mounts are involved.)  If you need to obtain the defini‐
       tion  of  the  blkcnt_t  or  blksize_t  types  from  <sys/stat.h>,  then   define
       _XOPEN_SOURCE with the value 500 or greater (before including any header files).


       POSIX.1-1990  did  not  describe the S_IFMT, S_IFSOCK, S_IFLNK, S_IFREG, S_IFBLK,
       S_IFDIR, S_IFCHR, S_IFIFO, S_ISVTX constants, but instead demanded the use of the
       macros  S_ISDIR(),  etc.   The  S_IF*  constants  are present in POSIX.1-2001 and
       later.


       The S_ISLNK() and S_ISSOCK() macros are not in POSIX.1-1996, but both are present
       in POSIX.1-2001; the former is from SVID 4, the latter from SUSv2.


       UNIX  V7  (and  later  systems)  had S_IREAD, S_IWRITE, S_IEXEC, where POSIX pre‐
       scribes the synonyms S_IRUSR, S_IWUSR, S_IXUSR.


   Other systems
       Values that have been (or are) in use on various systems:


       hex    name       ls   octal    description
       f000   S_IFMT          170000   mask for file type
       0000                   000000   SCO out-of-service inode; BSD
                                       unknown type; SVID-v2 and XPG2 have
                                       both 0 and 0100000 for ordinary file
       1000   S_IFIFO    p|   010000   FIFO (named pipe)
       2000   S_IFCHR    c    020000   character special (V7)
       3000   S_IFMPC         030000   multiplexed character special (V7)
       4000   S_IFDIR    d/   040000   directory (V7)
       5000   S_IFNAM         050000   XENIX named special file with two
                                       subtypes, distinguished by st_rdev
                                       values 1, 2
       0001   S_INSEM    s    000001   XENIX semaphore subtype of IFNAM
       0002   S_INSHD    m    000002   XENIX shared data subtype of IFNAM
       6000   S_IFBLK    b    060000   block special (V7)
       7000   S_IFMPB         070000   multiplexed block special (V7)
       8000   S_IFREG    -    100000   regular (V7)
       9000   S_IFCMP         110000   VxFS compressed
       9000   S_IFNWK    n    110000   network special (HP-UX)
       a000   S_IFLNK    l@   120000   symbolic link (BSD)
       b000   S_IFSHAD        130000   Solaris shadow inode for ACL (not
                                       seen by user space)
       c000   S_IFSOCK   s=   140000   socket (BSD; also "S_IFSOC" on VxFS)
       d000   S_IFDOOR   D>   150000   Solaris door
       e000   S_IFWHT    w%   160000   BSD whiteout (not used for inode)
       0200   S_ISVTX         001000   sticky bit: save swapped text even
                                       after use (V7)
                                       reserved (SVID-v2)
                                       On nondirectories: don't cache this
                                       file (SunOS)
                                       On directories: restricted deletion
                                       flag (SVID-v4.2)
       0400   S_ISGID         002000   set-group-ID on execution (V7)
                                       for directories: use BSD semantics
                                       for propagation of GID
       0400   S_ENFMT         002000   System V file locking enforcement
                                       (shared with S_ISGID)
       0800   S_ISUID         004000   set-user-ID on execution (V7)
       0800   S_CDF           004000   directory is a context dependent
                                       file (HP-UX)


       A sticky command appeared in Version 32V AT&T UNIX.


NOTES
       Since  kernel  2.5.48,  the stat structure supports nanosecond resolution for the
       three file timestamp fields.  Glibc exposes  the  nanosecond  component  of  each
       field  using names of the form st_atim.tv_nsec if the _BSD_SOURCE or _SVID_SOURCE
       feature test macro is defined.  These fields are specified in POSIX.1-2008,  and,
       starting   with   version   2.12,   glibc  also  exposes  these  field  names  if
       _POSIX_C_SOURCE is defined with the value 200809L or greater, or _XOPEN_SOURCE is
       defined  with the value 700 or greater.  If none of the aforementioned macros are
       defined, then the nanosecond values are exposed with names of  the  form  st_ati‐
       mensec.  On file systems that do not support subsecond timestamps, the nanosecond
       fields are returned with the value 0.


       On Linux, lstat() will generally not trigger automounter action,  whereas  stat()
       will (but see fstatat(2)).


       For most files under the /proc directory, stat() does not return the file size in
       the st_size field; instead the field is returned with the value 0.


   Underlying kernel interface
       Over time, increases in the size of the stat structure have led to three  succes‐
       sive  versions  of  stat():  sys_stat()  (slot __NR_oldstat), sys_newstat() (slot
       __NR_stat), and sys_stat64() (new in kernel 2.4; slot  __NR_stat64).   The  glibc
       stat()  wrapper function hides these details from applications, invoking the most
       recent version of the system call provided  by  the  kernel,  and  repacking  the
       returned  information  if  required  for old binaries.  Similar remarks apply for
       fstat() and lstat().


EXAMPLE
       The following program calls stat() and displays selected fields in  the  returned
       stat structure.


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


       int
       main(int argc, char *argv[])
       #include <sys/types.h>
       #include <sys/stat.h>
       #include <time.h>
       #include <stdio.h>
       #include <stdlib.h>


       int
       main(int argc, char *argv[])
       {
           struct stat sb;


           if (argc != 2) {
               fprintf(stderr, "Usage: %s <pathname>\n", argv[0]);
               exit(EXIT_FAILURE);
           }


           if (stat(argv[1], &sb) == -1) {
               fprintf(stderr, "Usage: %s <pathname>\n", argv[0]);
               exit(EXIT_FAILURE);
           }


           if (stat(argv[1], &sb) == -1) {
               perror("stat");
               exit(EXIT_FAILURE);
           }


           printf("File type:                ");


           switch (sb.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;
       feature test macro is defined.  These fields are specified in POSIX.1-2008,  and,
       starting   with   version   2.12,   glibc  also  exposes  these  field  names  if
       _POSIX_C_SOURCE is defined with the value 200809L or greater, or _XOPEN_SOURCE is
       defined  with the value 700 or greater.  If none of the aforementioned macros are
       defined, then the nanosecond values are exposed with names of  the  form  st_ati‐
       mensec.  On file systems that do not support subsecond timestamps, the nanosecond
       fields are returned with the value 0.


       On Linux, lstat() will generally not trigger automounter action,  whereas  stat()
       will (but see fstatat(2)).


       For most files under the /proc directory, stat() does not return the file size in
       the st_size field; instead the field is returned with the value 0.


   Underlying kernel interface
       Over time, increases in the size of the stat structure have led to three  succes‐
       sive  versions  of  stat():  sys_stat()  (slot __NR_oldstat), sys_newstat() (slot
       __NR_stat), and sys_stat64() (new in kernel 2.4; slot  __NR_stat64).   The  glibc
       stat()  wrapper function hides these details from applications, invoking the most
       recent version of the system call provided  by  the  kernel,  and  repacking  the
       returned  information  if  required  for old binaries.  Similar remarks apply for
       fstat() and lstat().


EXAMPLE
       The following program calls stat() and displays selected fields in  the  returned
       stat structure.


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


       int
       main(int argc, char *argv[])
       {
           struct stat sb;


           if (argc != 2) {
               fprintf(stderr, "Usage: %s <pathname>\n", argv[0]);
               exit(EXIT_FAILURE);
           }


           if (stat(argv[1], &sb) == -1) {
               perror("stat");
               exit(EXIT_FAILURE);
           }


           printf("File type:                ");


           switch (sb.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) sb.st_ino);


           printf("Mode:                     %lo (octal)\n",
                   (unsigned long) sb.st_mode);


           printf("Link count:               %ld\n", (long) sb.st_nlink);
           printf("Ownership:                UID=%ld   GID=%ld\n",
                   (long) sb.st_uid, (long) sb.st_gid);


           printf("Preferred I/O block size: %ld bytes\n",
                   (long) sb.st_blksize);
           printf("File size:                %lld bytes\n",
                   (long long) sb.st_size);
           printf("Blocks allocated:         %lld\n",
                   (long long) sb.st_blocks);


           printf("Last status change:       %s", ctime(&sb.st_ctime));
           printf("Last file access:         %s", ctime(&sb.st_atime));
           printf("Last file modification:   %s", ctime(&sb.st_mtime));


           exit(EXIT_SUCCESS);
       }


SEE ALSO
       access(2),  chmod(2),  chown(2),  fstatat(2),  readlink(2),  utime(2),  capabili‐
       ties(7), symlink(7)


COLOPHON
       This page is part of release 3.53 of the Linux man-pages project.  A  description
       of   the  project,  and  information  about  reporting  bugs,  can  be  found  at
       http://www.kernel.org/doc/man-pages/.


stat函数讲解


表头文件:    #include <sys/stat.h>
             #include <unistd.h>
定义函数:    int stat(const char *file_name, struct stat *buf);
函数说明:    通过文件名filename获取文件信息，并保存在buf所指的结构体stat中
返回值:      执行成功则返回0，失败返回-1，错误代码存于errno


错误代码:
    ENOENT         参数file_name指定的文件不存在
    ENOTDIR        路径中的目录存在但却非真正的目录
    ELOOP          欲打开的文件有过多符号连接问题，上限为16符号连接
    EFAULT         参数buf为无效指针，指向无法存在的内存空间
    EACCESS        存取文件时被拒绝
    ENOMEM         核心内存不足
    ENAMETOOLONG   参数file_name的路径名称太长




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


int main() {
    struct stat buf;
    stat("/etc/hosts", &buf);
    printf("/etc/hosts file size = %d\n", buf.st_size);
}




-----------------------------------------------------
struct stat {
    dev_t         st_dev;       //文件的设备编号
    ino_t         st_ino;       //节点
    mode_t        st_mode;      //文件的类型和存取的权限
    nlink_t       st_nlink;     //连到该文件的硬连接数目，刚建立的文件值为1
    uid_t         st_uid;       //用户ID
    gid_t         st_gid;       //组ID
    dev_t         st_rdev;      //(设备类型)若此文件为设备文件，则为其设备编号
    off_t         st_size;      //文件字节数(文件大小)
    unsigned long st_blksize;   //块大小(文件系统的I/O 缓冲区大小)
    unsigned long st_blocks;    //块数
    time_t        st_atime;     //最后一次访问时间
    time_t        st_mtime;     //最后一次修改时间
    time_t        st_ctime;     //最后一次改变时间(指属性)
};


先前所描述的st_mode 则定义了下列数种情况：
    S_IFMT   0170000    文件类型的位遮罩
    S_IFSOCK 0140000    scoket
    S_IFLNK 0120000     符号连接
    S_IFREG 0100000     一般文件
    S_IFBLK 0060000     区块装置
    S_IFDIR 0040000     目录
    S_IFCHR 0020000     字符装置
    S_IFIFO 0010000     先进先出


    S_ISUID 04000     文件的(set user-id on execution)位
    S_ISGID 02000     文件的(set group-id on execution)位
    S_ISVTX 01000     文件的sticky位


    S_IRUSR(S_IREAD) 00400     文件所有者具可读取权限
    S_IWUSR(S_IWRITE)00200     文件所有者具可写入权限
    S_IXUSR(S_IEXEC) 00100     文件所有者具可执行权限


    S_IRGRP 00040             用户组具可读取权限
    S_IWGRP 00020             用户组具可写入权限
    S_IXGRP 00010             用户组具可执行权限


    S_IROTH 00004             其他用户具可读取权限
    S_IWOTH 00002             其他用户具可写入权限
    S_IXOTH 00001             其他用户具可执行权限


    上述的文件类型在POSIX中定义了检查这些类型的宏定义：
    S_ISLNK (st_mode)    判断是否为符号连接
    S_ISREG (st_mode)    是否为一般文件
    S_ISDIR (st_mode)    是否为目录
    S_ISCHR (st_mode)    是否为字符装置文件
    S_ISBLK (s3e)        是否为先进先出
    S_ISSOCK (st_mode)   是否为socket




    若一目录具有sticky位(S_ISVTX)，则表示在此目录下的文件只能被该文件所有者、此目录所有者或root来删除或改名。


-----------------------------------------------------
struct statfs {
    long    f_type;          //文件系统类型
    long    f_bsize;         //块大小
    long    f_blocks;        //块多少
    long    f_bfree;         //空闲的块
    long    f_bavail;        //可用块
    long    f_files;         //总文件节点
    long    f_ffree;         //空闲文件节点
    fsid_t f_fsid;           //文件系统id
    long    f_namelen;       //文件名的最大长度
    long    f_spare[6];      //spare for later
};


stat、fstat和lstat函数(UNIX)




#include<sys/types.h>
#include<sys/stat.h>
int stat(const char *restrict pathname, struct stat *restrict buf);
提供文件名字，获取文件对应属性。感觉一般是文件没有打开的时候这样操作。
int fstat(int filedes, struct stat *buf);
通过文件描述符获取文件对应的属性。文件打开后这样操作
int lstat(const char *restrict pathname, struct stat *restrict buf);
连接文件


三个函数的返回：若成功则为0，若出错则为-1
给定一个pathname，stat函数返回一个与此命名文件有关的信息结构，fstat函数获得已在描述符filedes上打开的文件的有关信息。lstat函数类似于stat，但是当命名的文件是一个符号连接时，lstat返回该符号连接的有关信息，而不是由该符号连接引用的文件的信息。


第二个参数是个指针，它指向一个我们应提供的结构。这些函数填写由buf指向的结构。该结构的实际定义可能随实现而有所不同，但其基本形式是：


struct stat{
mode_t st_mode;   /*file tpye &mode (permissions)*/
ino_t st_ino;     /*i=node number (serial number)*/
dev_t st_rdev;   /*device number for special files*/
nlink_t st_nlink; /*number of links*/
uid_t    st_uid; /*user id of owner*/
gid_t    st_gid; /*group ID of owner*/
off_t   st_size; /*size in bytes for regular files*/
time_t st_atime; /*time of last access*/
time_t st_mtime; /*time of last modification*/
time_t st_ctime; /*time of last file status change*/
long st_blksize; /*best I/O block size */
long st_blocks; /*number of 512-byte blocks allocated*/
};
   注意，除最后两个以外，其他各成员都为基本系统数据类型。我们将说明此结构的每个成员以了解文件属性。
  
使用stat函数最多的可能是ls-l命令，用其可以获得有关一个文件的所有信息。
1 函数都是获取文件（普通文件，目录，管道，socket，字符，块（）的属性。
函数原型
#include <sys/stat.h>


int stat(const char *restrict pathname, struct stat *restrict buf);
提供文件名字，获取文件对应属性。
int fstat(int filedes, struct stat *buf);
通过文件描述符获取文件对应的属性。
int lstat(const char *restrict pathname, struct stat *restrict buf);
连接文件描述命，获取文件属性。
2 文件对应的属性
struct stat {
        mode_t     st_mode;       //文件对应的模式，文件，目录等
        ino_t      st_ino;       //inode节点号
        dev_t      st_dev;        //设备号码
        dev_t      st_rdev;       //特殊设备号码
        nlink_t    st_nlink;      //文件的连接数
        uid_t      st_uid;        //文件所有者
        gid_t      st_gid;        //文件所有者对应的组
        off_t      st_size;       //普通文件，对应的文件字节数
        time_t     st_atime;      //文件最后被访问的时间
        time_t     st_mtime;      //文件内容最后被修改的时间
        time_t     st_ctime;      //文件状态改变时间
        blksize_t st_blksize;    //文件内容对应的块大小
        blkcnt_t   st_blocks;     //伟建内容对应的块数量
      };


可以通过上面提供的函数，返回一个结构体，保存着文件的信息。