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STAT(2)			   Linux Programmer's Manual		       STAT(2)

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():
	   /* glibc 2.19 and earlier */	_BSD_SOURCE ||
	   /* Since glibc 2.20 */_DEFAULT_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	infor-
       mation 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	archi-
       tectures.   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)	repre-
       sents.

       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  in-
       efficient 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 di-
       rectory	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  ex-
       ecve(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  informa-
       tion (i.e., owner, group, link count, mode, etc.).

       The  following  mask  values are	defined	for the	file type component of
       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

       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  de-
       fined  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 ex-
       posed 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), _DE-
       FAULT_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 permissions	compo-
       nent of the st_mode field:

	   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	direc-
       tory, 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 di-
       rectory 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 defini-
	      tion.

       AT_SYMLINK_NOFOLLOW
	      If  pathname  is a symbolic link,	do not dereference it: instead
	      return information about the link	itself,	like lstat().  (By de-
	      fault, 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 de-
       manded 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 un-
				       known 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 Reiserfs.  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  de-
       tails 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>\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
       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 3.74 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
       http://www.kernel.org/doc/man-pages/.

Linux				  2014-08-19			       STAT(2)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | VERSIONS | CONFORMING TO | NOTES | EXAMPLE | SEE ALSO | COLOPHON

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