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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 *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)):

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

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

DESCRIPTION

       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 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.

   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.

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

       st_nlink
              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.

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

       st_size
              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.

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

       st_blocks
              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.)

       st_atime
              This is the file's last access timestamp.

       st_mtime
              This is the file's last modification timestamp.

       st_ctime
              This is the file's last status change timestamp.

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

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

       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 not a valid open file descriptor.

       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  and
              AT_EMPTY_PATH was not specified in flags.

       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  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.)

NOTES

   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:

       __old_kernel_stat
              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().

EXAMPLE

       The following program calls lstat() 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>
       #include <sys/sysmacros.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 (lstat(argv[1], &sb) == -1) {
               perror("lstat");
               exit(EXIT_FAILURE);
           }

           printf("ID of containing device:  [%lx,%lx]\n",
                (long) major(sb.st_dev), (long) 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:            %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

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

COLOPHON

       This page is part of release 4.16 of the Linux man-pages project.  A  description  of  the
       project,  information  about  reporting  bugs, and the latest version of this page, can be
       found at https://www.kernel.org/doc/man-pages/.