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       stat, fstat, lstat, fstatat - get file status


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

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

       #include <fcntl.h>           /* Definition of AT_* constants */
       #include <sys/stat.h>

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

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

           /* glibc 2.19 and earlier */ _BSD_SOURCE
               || /* Since glibc 2.20 */ _DEFAULT_SOURCE
               || _XOPEN_SOURCE >= 500
               || /* Since glibc 2.10: */ _POSIX_C_SOURCE >= 200112L

           Since glibc 2.10:
               _POSIX_C_SOURCE >= 200809L
           Before glibc 2.10:


       These  functions return information about a file, in the buffer pointed to by statbuf.  No
       permissions are required on the file itself, but—in the case  of  stat(),  fstatat(),  and
       lstat()—execute (search) permission is required on all of the directories in pathname that
       lead to the file.

       stat() and fstatat() retrieve information about the  file  pointed  to  by  pathname;  the
       differences for fstatat() are described below.

       lstat()  is  identical  to  stat(),  except  that  if pathname is a symbolic link, then it
       returns information about the link itself, not the file that the link refers to.

       fstat() is identical to stat(), except that the file about  which  information  is  to  be
       retrieved is specified by the file descriptor fd.

   The stat structure
       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;        /* 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

       Note:  the order of fields in the stat structure varies somewhat across architectures.  In
       addition, the definition above does not show the padding bytes that may be present between
       some  fields  on  various  architectures.  Consult the glibc and kernel source code if you
       need to know the details.

       Note: for performance and simplicity reasons, different fields in the stat  structure  may
       contain  state information from different moments during the execution of the system call.
       For example, if st_mode or st_uid is changed by another process  by  calling  chmod(2)  or
       chown(2),  stat()  might  return  the old st_mode together with the new st_uid, or the old
       st_uid together with the new st_mode.

       The fields in the stat structure are as follows:

       st_dev This 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.)

       st_ino This field contains the file's inode number.

              This field contains the file type and mode.  See inode(7) for further information.

              This field contains the number of hard links to the file.

       st_uid This field contains the user ID of the owner of the file.

       st_gid This field contains the ID of the group owner of the file.

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

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

              This field gives the "preferred" block size for efficient filesystem I/O.

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

              This is the time of the last access of file data.

              This is the time of last modification of file data.

              This is the file's last status change timestamp (time of last change to the inode).

       For further information on the above fields, see inode(7).

       The fstatat() system call is a more general interface for accessing file information which
       can still provide exactly the behavior of each of stat(), lstat(), and fstat().

       If  the  pathname  given  in  pathname is relative, then it is interpreted relative to the
       directory referred to by the file descriptor dirfd (rather than relative  to  the  current
       working  directory of the calling process, as is done by stat() and lstat() for a relative

       If pathname is relative and  dirfd  is  the  special  value  AT_FDCWD,  then  pathname  is
       interpreted  relative to the current working directory of the calling process (like stat()
       and lstat()).

       If pathname is absolute, then dirfd is ignored.

       flags can either be 0, or include one or more of the following flags ORed:

       AT_EMPTY_PATH (since Linux 2.6.39)
              If pathname is an empty string, operate on the file referred to by dirfd (which may
              have  been  obtained using the open(2) O_PATH flag).  In this case, dirfd can refer
              to any type of file, not just a directory, and the behavior of fstatat() is similar
              to that of fstat().  If dirfd is AT_FDCWD, the call operates on the current working
              directory.   This  flag  is  Linux-specific;  define  _GNU_SOURCE  to  obtain   its

       AT_NO_AUTOMOUNT (since Linux 2.6.38)
              Don't  automount  the  terminal  ("basename")  component  of  pathname  if  it is a
              directory that is an automount point.  This allows the caller to gather  attributes
              of an automount point (rather than the location it would mount).  Since Linux 4.14,
              also don't instantiate a nonexistent name in an on-demand directory  such  as  used
              for  automounter  indirect  maps.   This  flag has no effect if the mount point has
              already been mounted over.

              Both stat() and lstat() act as though AT_NO_AUTOMOUNT was set.

              The AT_NO_AUTOMOUNT can be used in tools that scan  directories  to  prevent  mass-
              automounting of a directory of automount points.

              This flag is Linux-specific; define _GNU_SOURCE to obtain its definition.

              If  pathname  is a symbolic link, do not dereference it: instead return information
              about the link itself, like lstat().  (By default, fstatat() dereferences  symbolic
              links, like stat().)

       See openat(2) for an explanation of the need for fstatat().


       On success, zero is returned.  On error, -1 is returned, and errno is set appropriately.


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

       EBADF  fd is not a valid open file descriptor.

       EFAULT Bad address.

       ELOOP  Too many symbolic links encountered while traversing the path.

              pathname is too long.

       ENOENT A component of pathname does not exist or is a dangling symbolic link.

       ENOENT pathname is an empty string and AT_EMPTY_PATH was not specified in flags.

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

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

              pathname 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

       The following additional errors can occur for fstatat():

       EBADF  dirfd is not a valid file descriptor.

       EINVAL Invalid flag specified in flags.

              pathname is relative and dirfd is a file descriptor referring to a file other  than
              a directory.


       fstatat()  was  added  to  Linux  in  kernel 2.6.16; library support was added to glibc in
       version 2.4.


       stat(), fstat(), lstat(): SVr4, 4.3BSD, POSIX.1-2001, POSIX.1.2008.

       fstatat(): POSIX.1-2008.

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


   Timestamp fields
       Older  kernels  and older standards did not support nanosecond timestamp fields.  Instead,
       there were three timestamp fields—st_atime, st_mtime, and st_ctime—typed  as  time_t  that
       recorded timestamps with one-second precision.

       Since  kernel 2.5.48, the stat structure supports nanosecond resolution for the three file
       timestamp fields.  The nanosecond components of each timestamp are available via names  of
       the  form  st_atim.tv_nsec,  if  suitable  feature  test  macros  are defined.  Nanosecond
       timestamps were standardized in POSIX.1-2008,  and,  starting  with  version  2.12,  glibc
       exposes  the  nanosecond  component  names  if  _POSIX_C_SOURCE  is defined with the value
       200809L or greater, or _XOPEN_SOURCE is defined with the value 700 or greater.  Up to  and
       including  glibc  2.19,  the definitions of the nanoseconds components are also defined if
       _BSD_SOURCE or _SVID_SOURCE is defined.  If none of the aforementioned macros are defined,
       then the nanosecond values are exposed with names of the form st_atimensec.

   C library/kernel differences
       Over  time,  increases  in  the  size  of  the stat structure have led to three successive
       versions of stat(): sys_stat() (slot __NR_oldstat), sys_newstat()  (slot  __NR_stat),  and
       sys_stat64()  (slot __NR_stat64) on 32-bit platforms such as i386.  The first two versions
       were already present in Linux 1.0 (albeit with different names); the  last  was  added  in
       Linux 2.4.  Similar remarks apply for fstat() and lstat().

       The  kernel-internal  versions  of the stat structure dealt with by the different versions
       are, respectively:

              The original structure, with rather narrow fields, and no padding.

       stat   Larger st_ino field and padding added to various parts of the  structure  to  allow
              for future expansion.

       stat64 Even  larger  st_ino  field,  larger  st_uid  and  st_gid fields to accommodate the
              Linux-2.4 expansion of UIDs and GIDs to 32 bits, and various other enlarged  fields
              and  further  padding  in  the  structure.   (Various padding bytes were eventually
              consumed in Linux 2.6,  with  the  advent  of  32-bit  device  IDs  and  nanosecond
              components for the timestamp fields.)

       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.

       On  modern  64-bit  systems, life is simpler: there is a single stat() system call and the
       kernel deals with a stat structure that contains fields of a sufficient size.

       The underlying system call employed by the glibc fstatat() wrapper  function  is  actually
       called fstatat64() or, on some architectures, newfstatat().


       The  following  program  calls  lstat()  and displays selected fields in the returned stat

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

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

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

           if (lstat(argv[1], &sb) == -1) {

           printf("ID of containing device:  [%jx,%jx]\n",
                   (uintmax_t) major(sb.st_dev),
                   (uintmax_t) minor(sb.st_dev));

           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:            %ju\n", (uintmax_t) sb.st_ino);

           printf("Mode:                     %jo (octal)\n",
                   (uintmax_t) sb.st_mode);

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

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



       ls(1),  stat(1),  access(2),  chmod(2),   chown(2),   readlink(2),   statx(2),   utime(2),
       capabilities(7), inode(7), symlink(7)


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