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NAME

       stat, fstat, lstat, fstatat - get file status

SYNOPSIS

       #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)):

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

       fstatat():
           Since glibc 2.10:
               _XOPEN_SOURCE >= 700 || _POSIX_C_SOURCE >= 200809L
           Before glibc 2.10:
               _ATFILE_SOURCE

DESCRIPTION

       These functions return information about a file, in the buffer  pointed
       to by stat.  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  the  glibc and kernel source code if you
       need to know the details.

       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.).

       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 directory, and by a privileged process.

   fstatat()
       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 stat()).

       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.

       AT_SYMLINK_NOFOLLOW
              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().

RETURN VALUE

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

ERRORS

       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.

       ENAMETOOLONG
              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).

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

       EOVERFLOW
              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 bytes.

       The following additional errors can occur for fstatat():

       EBADF  dirfd is not a valid file descriptor.

       EINVAL Invalid flag specified in flags.

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

VERSIONS

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

CONFORMING TO

       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  component  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 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 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.

NOTES

       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 Resierfs.  On filesystems that do not support subsecond timestamps,
       the nanosecond fields are returned with the value 0.

   Underlying kernel interface
       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() (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().

       The underlying system call employed  by  the  glibc  fstatat()  wrapper
       function is actually called fstatat64().

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>
", 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
");            break;
           case S_IFCHR:  printf("character device
");        break;
           case S_IFDIR:  printf("directory
");               break;
           case S_IFIFO:  printf("FIFO/pipe
");               break;
           case S_IFLNK:  printf("symlink
");                 break;
           case S_IFREG:  printf("regular file
");            break;
           case S_IFSOCK: printf("socket
");                  break;
           default:       printf("unknown?
");                break;
           }

           printf("I-node number:            %ld
", (long) sb.st_ino);

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

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

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

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

COLOPHON

       This  page  is  part of release 3.65 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/.



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