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

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

       int fstatat(int dirfd, const char *pathname, struct stat *buf,
                   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 ||
           || /* Since glibc 2.10: */ _POSIX_C_SOURCE >= 200112L

           Since glibc 2.10:
               _XOPEN_SOURCE >= 700 || _POSIX_C_SOURCE >= 200809L
           Before glibc 2.10:


       These  functions  return  information  about  a file, in the buffer pointed to by buf.  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 it 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.

       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 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 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 symbolic 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  filesystem  I/O.
       (Writing to a file in smaller chunks may cause an inefficient read-modify-rewrite.)

       Not  all of the Linux filesystems implement all of the time fields.  Some filesystem 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 relatime 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 routines,  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.).

       POSIX  refers to the st_mode bits corresponding to the mask S_IFMT (see below) as the file
       type, the 12 bits corresponding to the mask 07777 as the file  mode  bits  and  the  least
       significant 9 bits (0777) as the file permission bits.

       The following mask values are defined for the file type of the st_mode field:

           S_IFMT     0170000   bit mask for the file type bit field

           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

       Thus, to test for a regular file (for example), one could write:

           stat(pathname, &sb);
           if ((sb.st_mode & S_IFMT) == S_IFREG) {
               /* Handle regular file */

       Because  tests  of  the  above  form are common, additional macros are defined by POSIX to
       allow the test of the file type in st_mode to be written more concisely:

           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 preceding code snippet could thus be rewritten as:

           stat(pathname, &sb);
           if (S_ISREG(sb.st_mode)) {
               /* Handle regular file */

       The definitions of most of the above file type test macros are  provided  if  any  of  the
       following  feature  test  macros  is  defined:  _BSD_SOURCE  (in  glibc 2.19 and earlier),
       _SVID_SOURCE (in glibc 2.19 and earlier), or _DEFAULT_SOURCE (in glibc  2.20  and  later).
       In  addition,  definitions  of  all of the above macros except S_IFSOCK and S_ISSOCK() are
       provided if _XOPEN_SOURCE is defined.  The definition of S_IFSOCK can also be  exposed  by
       defining _XOPEN_SOURCE with a value of 500 or greater.

       The  definition  of  S_ISSOCK()  is exposed if any of the following feature test macros is
       defined: _BSD_SOURCE (in glibc 2.19 and  earlier),  _DEFAULT_SOURCE  (in  glibc  2.20  and
       later),  _XOPEN_SOURCE  with a value of 500 or greater, or _POSIX_C_SOURCE with a value of
       200112L or greater.

       The following mask values are defined for the file mode component of the st_mode field:

           S_ISUID     04000   set-user-ID bit
           S_ISGID     02000   set-group-ID bit (see below)
           S_ISVTX     01000   sticky bit (see below)

           S_IRWXU     00700   owner has read, write, and execute permission
           S_IRUSR     00400   owner has read permission
           S_IWUSR     00200   owner has write permission
           S_IXUSR     00100   owner has execute permission

           S_IRWXG     00070   group has read, write, and execute permission
           S_IRGRP     00040   group has read permission
           S_IWGRP     00020   group has write permission
           S_IXGRP     00010   group has execute permission

           S_IRWXO     00007   others (not in group) have read,  write,  and
                               execute permission
           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 directory, and by a
       privileged process.

       The fstatat() system call operates in exactly the same  way  as  stat(),  except  for  the
       differences described here.

       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() for a relative pathname).

       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

       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).  If dirfd is AT_FDCWD, the  call
              operates  on  the  current working directory.  In this case, dirfd can refer to any
              type  of  file,  not  just  a  directory.   This  flag  is  Linux-specific;  define
              _GNU_SOURCE to obtain its definition.

       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).  This flag can be
              used in tools that scan directories to prevent mass-automounting of a directory  of
              automount  points.   The  AT_NO_AUTOMOUNT flag has no effect if the mount point has
              already been mounted over.  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 bad.

       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 pathname is an empty string.

       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.)  If you need to obtain the definition 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(),
       and so on.  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  prescribes  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.


       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.

   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 the _BSD_SOURCE or _SVID_SOURCE feature test macro is defined.
       Nanosecond timestamps are nowadays standardized, starting with POSIX.1-2008, and, starting
       with version 2.12, glibc also 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.  If none of the aforementioned macros are defined, then the nanosecond  values
       are exposed with names of the form st_atimensec.

       Nanosecond  timestamps  are  supported  on XFS, JFS, Btrfs, and ext4 (since Linux 2.6.23).
       Nanosecond timestamps are not supported in ext2, ext3, and Reiserfs.  On filesystems  that
       do not support subsecond timestamps, the nanosecond fields are returned with the value 0.

   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  stat()  and  displays selected fields in the returned stat

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

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

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

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

           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));



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


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